i really need help. I am in love with her.

So me and my ex dated for a few months. I was a complete AFC near the end and got super jealous of her because she was hanging around other guys and kinda had feelings for one of them. I got really clingy, told her i loved her alot (she was the one who said it first though), etc. Then she broke up with me. At first, i flipped and was begging to get back together, etc (all that bad AFC stuff). This really ruined our chances of getting back together.

Then, I bought Matt Huston's ex2 system. I went through the no contact month, and by week 3 she was contacting me, telling our mutual friends how much she misses me, etc. We hung out, like the system suggested. I acted like a complete stud (lol no overconfidence) displaying alot of the qualities of an attractive man. We both had a great time, and afterwards she told me "That was SUPER fun. I really like just being friends, its so much more fun and chill." Then she proceeded to message me and talk to me all the time throughout that day, going out of her way while with her friends to do so. It was like before we broke up. It was great. I kept displaying all the attractive qualities (or so i believe...). Then we hung out with a bunch of friends, and it was fun but near the start i said that we "arent really friends." i took it back almost immediately, but she seemed hurt, but then she forgave me and was chill.

we were good for about a week, then i said that "i think i still love you, and wish we could start things over." She said "i feel the exact same way." then we moved on from talking about that and talked normally and joked around for awhile. then all of a sudden she responds extremely b*tchy at me, then insults every aspect of my life and deletes me on facebook, then when we see eachother in person (same athletic team) she insults me or ignores me or talks crap about me behind my back to my friends. she said she "is done with me and realized that i am a d*ckhead".

what am i supposed to do? i am legitimately in love with this girl. should i go for another no contact month, or talk to her about the real reason she suddenly got super pissed, or what?

thanks guys, any help is appreciated.