I find it hard to support your decision to let yourself fall for a girl who was attached to another man but that being said I'll try to be objective as possible. Keep in mind though you were asking for problems getting into a situation like this. The problem is she may have broken up with him based on your pressing the issue, not because she wanted to. You said "don't make a decision based on my feelings" but the truth is that was a little manipulative. Just mentioning it put pressure on her and then you said the part about your feelings just to deflect the responsibility. That's how I see it. Maybe she wasn't sure and now you're feeling the repercussions of this. She's still undecided and you're at a disadvantage, not only being long distance, but because you're the other man.

now I pose a question to you. I think that both of you were wrong for even getting involved but even so here is the question: do you really want to be with a woman that can get herself mixed up with another guy while supposedly being attached to one already? Who's to say she won't do the same thing to you? Of course you're not innocent in this but at the same time you're in for some turbulent waters ahead.

I don't know what else to tell you other than find a woman that is actually available before you start having sex and dating them.

Sorry I can't be more helpful
~s4