I have worried about this a lot in the past, to the point where it's become obsessive at times. Even though I'm at a point in my life where I know I like girls and I'm not finding that guys do anything for me at all, I can't help but question. After all, my past before I got into therapy involved a lot of gay porn and gay fantasies. That all went away after I realized that those behaviors were just me acting out from the abuse, but the question still pops up sometimes, because as I said, how is it I did all that stuff and then figured out that I was actually straight?
All I can do is look at where I am and try to realize that thoughts are just thoughts, and don't define me or my actions. If one day it turns out that I fall in love with another guy, then so be it, I will have to accept that and move on. If not, I'm very much ok with that too, and I will have to get comfortable with the fact that certain things might trigger me in my life.
Another thing to consider - in my case, I have eyes, I'm not blind. I can say that a man is attractive or good looking without actually being attracted. Looks are looks! I have gay friends who will openly drop a "Damn, that girl looks fine!", but that doesn't mean they want to sleep with her.
Emotionally, do what feels right. I have many male friends, and while many of them are like brothers to me and know all about what I've been through, I don't think I can say I've ever felt like I was physically, emotionally or romantically attracted to them. Most of my female friends on the other hand were crushes that I couldn't get the courage up to ask out, and as a result made me their friend by default. Nothing wrong with that either, just that it kind of kills me to hear girls I like talking about their boyfriends in front of me. My fault for not stating my intentions though. Ultimately, I've realized that what I want more than anything else is for a girl to be in my life who loves me and accepts 100% what I went through and doesn't judge me for it. I feel like I could really get close with somebody like that and actually fall in love. Who knows though! As we are all too aware, life throws us curveballs.