Well I'm already borderline alchoholic, so I'm off to a good start.
My situation isn't as complicated as yours, although it's pretty similar. Basically there were some sparks between me and said girl one night but nothing came of it, and everyone was on drugs so it's hard to say if it was genuine anyways. Didn't talk to her for awhile, then all of sudden get a call out of the blue and start hanging out with her constantly, although she's back together with her first love at this point. Befriend said boyfriend and continue to hang around them constantly. Boyfriend starts to hate me because me and his girlfriend flirt so much and always have deep conversations that sometimes involve him, so he moves like 20 miles away with her. Still hang out with them occasionally but not as much since they live so far away. She's told me that she regrets moving in with him though, and they constantly fight. I'm surprised they're even still together honestly. At this point I feel like it's better to wait and let things play out as they will and hope for the best. It's more than obvious that we both have a thing for each other though, all of our friends have noticed and commented on it and her entire family gives us shit about it. Well, mostly me.
I'm not stranger to the friend zone either, shit sucks.