I don't think you should let it affect you unless it's something really big (like he killed somebody or something o_O haha jk) ... but if it is nagging you, then you can talk to him about it, and hopefully it'll reassure you some more.

I want to hear the juicy gossip....jk.
It depends on what it is really, if it concerns you or if it is something in his character that he can't change then yeah you should worry about it, but if it is not then I say let it go unless you want to go through the whole ordeal of explaining how you found out and then have to explain to him about your crazy, jealous, protective ways.
My girlfriend has changed me dramatically, for the better of course, and I appreciate that and her very much for it.

It shouldnt affect you. Don't let the past ruin the future- well unless his past was waay better than what he is now.

it's not really a big deal, unless your thing for being a guys first whatever.. is really that big of an issue. if it's such a big issue that dating someone hinges on that as one of the qualifications.

I thought you USED to be a crazy, jealous girlfriend. Look at that verb, girl. Past tense! Ignore those devilish "What ifs" on your shoulder. Just be happy that you have a great guy and a prosperous relationship with him.

Every relationship is different, so don't let things that happened in the past with different people carry over to your relationship with him today. He's a different person, and a different boyfriend, with you than he was with anyone else.

At this point, the only thing I could find out about my SO that would make me stop and think would be to learn that he's lied to me or purposely withheld information with the intention of keeping it from me. Even those things aren't necessarily a big deal; I have learned a few pieces of new information about him along the way that made me go, "Wait a minute, this is new. I thought you said something else before...? So which one is it?" However, none of it was regarding anything significant and I didn't feel uncomfortable by anything I learned, just confused about how I hadn't known about it before, because I could have sworn I had asked him and gotten a different answer.

In other words, don't let what you learn (or dig up!) influence your relationship with him, unless you discover that he's been dishonest with you and it makes you uncomfortable.

I don't think there's a point of bringing old things from two years ago up again. what happen happened and you can't change that. as long as you are happy with the guy, it's all good you know? until you have something to suspect, then you should talk to him about it.

you shouldn't be in a relationship where you want to "change guys" but be with them for who they are......moving on....

anyways, im also guilty for wanting to know about the past relationships of my current sig others (or interests in general). how their past relationships were, sometimes reflect on their personal character or view points in the present, and I think it's important that both parties are aware of how and where they've "come" from. but then again, most guys don't want to know about his new gf's exbf or history of it. if the girl talks about it, he won't shut her up too often but at the same time, he won't offer you inputs about his own relationships.

I've done this to my ex and I've been trying to curve my curiosity for my new interest. I mean, it'll come out at one point or another.....so don't think too much of it. I think if it's as bad as he has been known to be a cheater or a liar (or both) and he hasn't said anything about that, I'd worry a bit. But such things reveal themselves in time...

Jealousy, changing boyfriends, wanting to know EVERYTHING about a guy = psycho!