Yeah there is nothing much you can do.
I know how much you want to protect her and want the best for herself.
but.. remember we can't force people to do or like on what we want to.

Just let her know that you will always be there for her.
and pray to the God hopefully she will always happy ok.

p/s: yeah it is true about some girl addicted to sex and they care nothing more about the man's background.