How did she "lower herself" ? So she was in a relationship that wasn't healthy for a variety of reasons. She is NO longer in it , she is with you.

Do you love her? or has learning of this changed your view of her? Have you spoke to her about how all this makes you feel ? or are you just trying to process it all ?

Does it just bother you the types of sexual activity she had with him is something you find repulsive?