Kiya,
I have a list of several maybes for you. I am in NO WAY an expert. Your T if you have one or the others on this forum are likely better at this than I am. But here are my thoughts.

Maybe what you experienced was simply a physical response from being close to some one.

Maybe your defenses were down because she was a female.

Maybe she was just one of those attractive people in the world. I'm not sure what it is but there are some people who for whatever reason seem to attract others. I worked with a guy who from the moment I spoke to him on the phone during my interview I felt totally comfortable with him. He was the same way in person. He was an exceptional educator, mainly because students were simply drawn to him. I don't know what it really is about him.. its just something some people have.

Maybe you simply weren't threaten by her. When you were in close proximity to her it triggered a kind of sexual response. You said you had been in an abusive relationship(s). I think because of my past history I tend immediately connect physical proximity with a sexual advance. Often this initial assumption is incorrect and I find myself embarrassed by my assumptions.

Maybe the two of you had differ ideas of personal space and it confused you. I'm not sure where you are from but I personally had a great deal of trouble when first interacted with people from outside the US. I don't know if it is a cultural thing or what but I definitely struggle sometimes with personal space issues in these situations.

Maybe the fact that you felt attracted to someone indicates that you are starting to heal from your abuse and your brain/body is signaling that you might be ready to consider dating again.

Maybe....

I understand your concern about the straight or not so straight issue, but one encounter is not going to turn you gay. My personal advice is relax, don't over think the situation, and try to be open to what comes. There could be a million reason you responded that way at that particular moment. The fact that you demonstrated an interest in connecting with another person was probably a good thing.