Adding to what Mutt said about the lack of sense of self (which, oddly is not one of my wife's traits that I can tell - at least not in the usual)...
Even with non-BPD cases, there can be shifts in sexuality. I've heard several men tell a story of being in a hetero marriage for years before realizing they were gay. I would imagine they struggled with it and attempted to suppress it for at least some time, possibly out of love for or commitment to the woman they were with (even if that love began to feel less romantic).
This is not to say that is the case here. Who knows? It may be a phase... perhaps she thinks she shifted hetero or perhaps she'll settle somewhere in the middle...? But, the point is that human sexuality, even for non-BPD's can change or other aspects can awaken.
So, is it possible? Yes. When you add the impulsiveness, lack of sense of self and general complexity of a pwBPD... I can see those factors playing in. But, it does not mean it has necessarily changed permanently or swung a full 180 degrees. She may be feeling it out still.
Remember growing up and people acting "grossed out" by thoughts of sex or being with someone else? Did it mean they weren't thinking about it back then? Sometimes it can be a "doth protest too much" scenario.
You said something at the end there...
she finally responded and told it was an example of "my prolonged emotional and pyschological abuse" of her. I know I was clingy, but I also know I never abused her. I tried really hard in the relationship and was committed to communication, growth, and being there for her.
Do not buy into that hook, line an sinker. Yes, sometimes us non's can lower yourself to points where we respond to manipulation or such in kind. It can happen. Like violence begets violence, if a person does not hold to their values, abuse can beget abuse. So, honest introspection may help. BUT...
...and this is a very serious but to consider...
It is very typical, from what I have read and personal experience, for us as the non's to take too much of the pwBPD's projection to heart and start to believe ourselves to be the problem much much more than we are. It can sometimes feel *we* are the crazy ones or the manipulators or abusers when we are not. It's a serious mind game.
Bear that in mind and do not fall into the trap of taking responsibility for what is not yours to take responsibility for. Easier said than done and I'll admit to falling into that trap myself.