I have always - since puberty - known I was bisexual. Sadly, many people do not accept bisexuality exists. I felt pressure to simply be gay/lesbian. That is not, however, who I am.
I have no way of knowing whether your ex is bisexual as well, but for anyone bisexual the balance can shift.
The biological clock does indeed starts ticking (well, it didnt in my case).
CSA can also affect our sexuality.
I suspect you both have considerable healing journeys to make - and indeed these may best be made separately, without torturing yourself about ehat she is doing.
I wish you all the best with that.