I would suggest that even though you might love her alot, dont invest too much in her.

I was "married" when I was 17 to a Polish girl who was way older than me. She also "cheated" on me. And since then I dont trust any girl. My current fiance is as close to being morally perfect you can be on earth, probably didnt do one bad thing in her life, yet I dont trust her at all. I just learned to live with it, and whatever happens will happen.