Aileen,

It was always the little things that tripped us up, we said. How many times did we have that conversation? Dozens. Hundreds, maybe. That the little things would set us off, and finally, you said, you couldn't stand the little things anymore, and you needed something big, something that we could reasonably use to end the marriage -- so you had an affair. That was how you explained it yesterday, once we'd divided everything up, once the papers were final, when we met for coffee to have the "can we still be friends" talk.

We'd fought for most of our marriage, and let's face it, we fought before that, too, over the size of the wedding and who would sit where and whether exes could come and if so, which. Little things. Every time we argued you said I was petty, that I would take some tiny incident, something you'd done or hadn't done or hadn't done right, and blow it out of proportion. You said I was petty and unforgiving and you might have been right, but we always had our best sex after fighting.

You argue passionately. Even when you're wrong, even when you know you're wrong -- God, especially then -- you fight with every inch you have. You don't raise your voice, you don't turn blue in the face, you don't throw things. Neither of us do. We're not "like that." We save that energy for sex, don't we? Instead of throwing plates at the wall we threw each other. Instead of slamming doors we slammed hips into the mattress. Instead of shouting we growled and mewled and groaned.

But you still fought. You'd argue and argue and argue, and even if it wasn't about something which had bothered me that much -- even if it was only that I was irritated you'd forgotten to tape the playoffs for me when I was working late, or that you made dinner plans for both of us without asking me first -- by the time we were done I was as pissed as you. Because that's what you wanted. Looking back, I realize that every time we hit a dry spell, it would end in an argument which brought up all the old bugaboos -- you'd go back to turning the TV on as you went to sleep, you'd use up the mouthwash but not put it on the grocery list, you'd flirt with my co-workers. All those things you knew would piss me off.

You liked pissing me off, Aileen, because you liked the way I fucked you when I was angry.

Don't get me wrong. It wasn't entirely you. If I hadn't done my share, we never would've been married so long. I made a point of teasing you about your sister after you gave me the standard "don't tell me my sister's hot" speech every woman gives. I'd single out things you did which I thought were beneath you, and more to the point beneath "my wife," whether those things were reading "The Horse Whisperer" or leaving a wet towel crumpled up on the floor after your shower.

Did I ever tell you about the time I fucked your sister, by the way?

I know I didn't. That wasn't so much a rhetorical question as it was a way to piss you off. See, I'm playing my part again. Cause the truth is, Aileen, we can't be friends. I don't really like you very much, and you don't like me, either. We want to "remain friends" because it makes us look like better people. It's Noble and Mature and Well-Adjusted.

You know what? We're not especially good people, and I don't think I give a shit.

How old is Carole again? She's about five years younger than you, I think. You always said you were jealous of her youth, but I remember you five years ago. She looks better than you did. Barring some kind of accident, or plastic surgery on your part, she always will. Better get used to it, cause jealousy might make you good in bed, but eventually that will wear off. Eventually it's just going to leave you ugly and bitter.

Carole's got your eyes, sure, although hers are brighter, more awake-looking. Your cheekbones, but somehow she's lost the "baby fat" her older sister claims to cling to. Bigger ass, which you pointed out once in a moment of your own pettiness, but hey, wouldn't you know it? That's in now. She wears low-rider jeans. She looks great in them.

All in all, she's sort of a prettier version of you. So look at it like this: imagine me fucking her, and however much I'm liking it, figure that seventy-five percent of that is because of things the two of you have in common. So seventy-five percent of my lust for your little sister, well, that part's just a compliment for you, isn't it?

How much am I pissing you off now?

Enough to make you wet?

You're wondering when it was. Do you know, I wonder that sometimes, too? I know where you met The Guy -- I'm not going to say his name -- but I don't know how it happened, how often, where, the mechanics of it, I guess you could say. The mechanics of the seduction, the blueprint of infidelity.

Let me spare you that, Aileen. You don't have to wonder.

Remember that time, I had the conference in Boston? I told you I hadn't had time to have dinner with your sister, and that was true, but only because we didn't bother with dinner. I went over to her apartment and fucked her. I could give you more details than that, but you know how it is, recounting how exactly you go from saying hi to someone on the phone to kicking your shoes off while you push their pants down -- you can never quite redraw the steps exactly, and once recounted, they never seem to add up.

So -- oh, maybe this phrasing will ring a bell for you -- "it just happened." Wasn't planned, by either of us. Had I always thought she was attractive? Yes, if I'd stopped to think about it. But I had never taken much of a look, because she was your sister, and I thought I loved you -- but let's face it, the main reason I fucked her is because she wasn't you. In a thousand wonderful ways, she wasn't you.

I watched some television while she got ready to go out for dinner, and at some point the clothes stopped going on and started coming off, her makeup still only half-applied. Maybe that much was planned: maybe she knew better than to risk leaving a lipstick mark on my shirt, one I might not catch.

Your name didn't come up once.

Not once did I think about you while I was kissing her, pulling her onto my lap and unhooking her bra while she yanked the half-buttoned blouse off, and if you grazed my thoughts while her fingers grazed my cock through my pants, it was only because it struck me how different her touch was. She wasn't needy. She wasn't proving anything. She just wanted what she wanted.

We were still half-dressed and she was wiping me from the corner of her mouth when we moved to the bedroom, and -- oh, but did you want details? Do you want to know if she sucked me differently than you did? If she took her time, licking and kissing and teasing before finally sucking me off, or if she just thrust her mouth over me and bobbed up and down until I burst?

You'll just have to guess.

Our clothes made a breadcrumb trail from the couch to the bedroom, that barely-more-than-a-closet she had at the time, the one with room for the bed and the dresser and not much else. When I fucked her I put my feet against the dresser at the end of the bed, using it as something to push against, so I could fuck her harder. She didn't bother screaming my name, she just screamed for the sake of it, on her hands and knees on top of the comforter, ramming her ass back against me and hissing every time I jabbed her. Do you want to know if I fucked her ass, taking the opportunity to get what you'd only give me once in a blue moon? You'll have to guess at that, too.

I'll tell you this: from behind, there's no resemblance between the two of you. She arches differently, holds herself differently, and her hair falls down over her face in a way which is dead sexy on her but would just make you look tired. There are these curves to her thighs, these little indentations like stretched-out dimples, which are just adorable when her legs clench. There's a cleft in the small of her back I couldn't stop running my fingers over.

You're thinking there's no way I could've been hard enough to fuck her that soon after she sucked my cock, that I hadn't been able to do that with you in years, and I don't blame you for thinking that. Maybe I was just more attracted to her. Maybe I was just tired of you.

Maybe every man in the world would rather fuck your sister, if he had the chance.

Afterwards -- much later, when I went to my hotel room just in time to check out -- we said the guilty things people say in situations like that, but we said them while touching each other, running hands under clothes, tracing fingertips over lips and necks, and yeah, there was affection there, because we'd always gotten along, but no, it wasn't love. It was just fucking, Aileen, never anything more than that and never anything less.

And I know you're pissed now. And you know I went to the Boston conference twice -- once before your affair, and once after. You want to know, did I cheat on you before you cheated on me?

You'll have to guess.

The best thing is, I know you, hon. I know how turned on you are right now. I know how badly you want to fuck, because you can't get pissed at me without wanting to fuck, not anymore, not after years of habit. It's like cigarettes and coffee, gin and tonic. So I figure you have two choices. If you want to be friends, forget the letter, call it even, and go fuck your new guy.

If you just want to piss each other off and fuck, you know where I live now.