I was in very much the same situation as you describe. Now after 15 years of marriage to my wife, I can tell you that I don't regret keeping my purity and that I don't care about the state of hers while we were dating. In the grand scheme of things, it really didn't matter (and no, that's not permission/excuse to keep doing anything wrong). We are very happy and the "other guy" that took her purity is so unimportant that she says it often seems like a dream from another life.
I used to focus on the past a lot. I mean A LOT! And I then learned something. If I'm always focused on what happened in the past (the rear view mirror), I can't fully pay attention and enjoy whats happening right now and what is coming. Try driving a car while you only look in the rear view mirror.
The way I see it, if my redeemer (and the creator and redeemer of the world) can forgive me for the things I've done, and has forgiven her for the things she's done, who am I to still hold it against her, even if I never vocalize it. Keeping it internal still builds resentment, and THAT is the real relationship killer.
I know, easier said than done... Pray, pray a lot, read the Bible, especially the stories of redemption and forgiveness. And even be honest with her about it, focusing on the fact that you don't want to feel that way. By not telling her, you set up the behavior of withholding how you feel, which becomes an easy way to keep the temporary peace, but takes away from your relational peace a little bit at a time.
I hope this helps.