Sadly, I think that the best predictor of future behavior is past behavior. I think many agree with this. Although you may act differently toward her and be a superior husband, your actions will not change her or who she is. She is not an evil person or a liar. But there is something--maybe an insecurity, maybe an emotional set off--that causes her to cheat. She needs to work on this heavily before entering another marriage. Even if she goes to a professional, she may still cheat again. I feel you may get very hurt. I think it may be wise to support her, go to a professional together (she should be willing and she should not get mad at you for finding out--you CAN and SHOULD be mad at her actions), and keep it an nonlegal commitment for awhile. 2.5 years is not too long, especially considering the length of your past marriages.

Overall, I think you are being too easy on her. You can love someone and hate their actions. You should hate her actions and should feel let down. I would be very, very cautious, especially since she was upfront but only about one. That is misleading and controling.

I wish you the best of luck.