Does anyone else find themselves very jealous of their partner's history, and if so how do you deal with that?

I have been dating my current g/f for a little over a year now. For the most part her romantic history has remained unknown to me, both for it not coming up and for myself explicitly pointing out that I didn’t really want to know it. But in interacting with some of her long time friends I’ve heard stories that would leave open a question in my head about her hooking up with someone or what have you at a party years ago. Until I would be able to ask her about it I would have these terrible worst case scenarios going through my head, and I would get pretty upset/jealous.. and then it would turn into some kind of argument/fight/incident with her later.

For example, over the weekend we were having dinner with a pair of her friends, and one of them brought up a story he’d heard from his g/f (the other friend) about a New Year’s party they had hosted that turned into a hook-up-fest or something to that effect. Immediately in my head I’m thinking, “oh great, my g/f hooked up with a bunch of guys in a drunken stupor…” But here’s the thing, it’s not like I haven’t done something to that effect. I’ve made out with multiple girls at the same party before, and hooked up with girls from parties…. and in the past it has never really bothered me that a girl I was with had done things like that in her past. I was always the “past is past, as long as you’re not doing it now that you’re with me” type of guy. In fact it turned out later the only person she’d made out with at that party was her b/f of the time. (though in fairness I had significantly brought myself down by the time we talked about it).

I think possibly this all has something to do with my most recent x g/f. We dated for nearly two years and got very very close. But it was a long distance relationship, and we hurt each other a number of times. Early in that relationship she left me to go back to her x b/f, purely for the sake of him being local to her and wanting a distraction before she went away to school. Later in the relationship there were issues of her cuddling with another guy, making out with another guy in a drunken stupor during a huge fight between us, and eventually holding hands and spending a lot of time with the guy she would eventually dump me for. I dunno if maybe I was so “burned” by that, that I’ve lost my care free attitude towards my SO’s past. I mean hell, I dated a girl who had had an abortion, a girl with a much higher “number” than my own… girls I’d seen making out with other guys… even guy friends of mine…. and that never bothered me. And not to get into my history or anything, but I highly doubt she’s done anything that I haven’t done myself. In fact I would dare say my past is far more extensive, at the very least in number of partners. So what room have I to be jealous even?

Anyone else face this? How do you deal with it? I did pretty well not letting it get to me that much over the weekend, but I’d by lying if I said it didn’t bother me at all.