So, I had a girl who seemed to like me a while back, and I went way overboard and told her a bunch of things about me that I shouldn't have.  She didn't bail immediately which made me say even more things I shouldn't and then eventually we lost contact, and the last thing I said was something like sorry for everything I'll leave you alone now.  Now every couple weeks I get this crazy idea of how I'm going to reconnect with this girl and I'll act normal this time.

Well, yesterday I happen to run into this girl and she seems happy enough to see me.  I text her and we have a perfectly fucking pleasant conversation, like nothing ever happened.  I broke it off before I managed to fuck anything up, but now I can't stop thinking about this girl again and I know there's no way she thinks about me this much because why the hell would she, we barely know each other.  

Anyways, I have no idea what the fuck to do I just know I can't stop myself from obsessing over anyone showing the slightest bit of interest in me because I'm so used to being passed over.  How do you stop this behavior?