I think that abuse can easily become a handy reason to deny one's sexuality. You just say to yourself "Well, I'm not really gay or bi, I'm just confused because of the abuse."
I also think that as long as one is influenced by society's non-acceptance of homosexuality, it will be very difficult to know if that notion is based on fact or bias.
I don't believe that being bisexual means that you can't have a monogamous relationship if you desire one, but neither do I believe that a meaningful relationship necessarily has to be a monogamous one.
I would say that I am in two very meaningful non-monogamous relationships right now with an older man and a younger one and both are a cherished part of my life.
I just think it's bad to limit yourself. I feel that if we survivors in general could spend less time thinking of reasons why we can't have a healthy relationship and more time thinking of reasons we can, we might all do a lot better!--- and that goes for me as well.