Boyfriend was with a girl that made my life miserable and I'm still upset. How can I not be?

My boyfriend and I have been dating for 17 months. We had a pretty bad first couple of months with him constantly lying and keeping communication ties open with people he had slept with. But he is completely different now. Literally, I am a lucky girl.

Except for one thing. I can’t get over his past. Let me start off by saying he’s slept with 40+ women (many of times unprotected because he was a drunken idiot, but no STDs…thank God), and he is my third. I have trouble with the idea that he tells me that these previous experiences were nothing and that ours is so much better. I mean, it’s like thrusting..how is it any different between people? Maybe it’s because I’ve only done it with people that I’ve cared about and not ones that I don’t actually know, but can someone clarify this? He says now that our sex is the best he’s ever had..but well..I don’t believe that because there were certain instances in time that he’s had sex outside, on airplanes, on beaches, on scaffolding…ugh it’s ridiculous. How can those experiences not be hot? Or for that matter be better than the times we have it…in…bed?

I particularly, (and talk about coincidence) can’t stand this specific girl he slept with AND liked. In college this girl tortured me. Literally, like an adult bully. My boyfriend met her while in graduate school together, liked her, and they slept together… more than once. Unprotected. Anyway, she actually had a boyfriend so they didn’t go anywhere. He met me a couple of months later, we went on our first date, it was a disaster, and then that night went to her place to try to get some (they didn’t have any though).

While we were dating he still called her pet names (behind my back) and originally lied about what was going on about their relationship.

I’m wondering about the whole hotness aspect of it all, how to get over his “relationship” with this girl who literally spent college making me miserable, and the fact that I feel like i have her used goods?