Mate you need to chill. Don't get upset/angry/pissed off over this sort of stuff.
First, talking to her about her 'problems' all night over her ex is the sort of thing a girl does to a guy friend - not someone she wants to fuck. So I'd definitely stop listening to her issues and being 'there for her'. That won't help.
Anyway as I said, you seem frustrated. If she picks up on those vibes, it can scream desperation and jealously a bit and you wouldn't want her to think that right. Big turn off. So what she was sitting with her ex? That shouldn't matter to you. Your a MAN.
Less asking loads of ifs and buts, just play your own game and be cool about it. Trust. Giving reasons and saying stuff like 'I've got all this, I get in shape, what more can she want?'....come on bro, have some style. Get her to chase that!
All the guys on here will tell you so much more on that and I don't know the details of your situation that well, but I think you need to relax and be cooler about this first off - definitely a different mindset anyway.
(Don't be put off by the fact I'm no regular poster here, I know my way around
) Good luck bro.