My ex-gf is acting weird. Why tho? She's the one who ended it.?

[James]

We use to be close friends. But she had feelings for me ever since we met. We broke up last day of school. It was mostly because we both have a lot of mental issues. Fast Forward to the new year. We talked a little not so much, I avoided contact with her. Few weeks later I couldn't take it anymore and out of anger i caused a bit of drama. It wasn't really that bad. Just a whole I want you out of here.(Note: we have the same group of friends) Few weeks go by. During those few weeks we got into big arguments I never really said anything I just stood there smiling while she yelled and hit me. After this I started completely avoiding her. Few weeks past by again. She’s starting to act weird now. I'll be talking to a friend she will just jump in and say stuff to me like "Your mom." Nothing too mean. She would hit me on the head not hard but softly. She will basically do anything to start a little argument with me. My friend was doing a singing project. I volunteered first. She after I did. Before our first practice session, she was pouting that her hat looked weird on her. Out of the blue I just said it looked fine and said it looked good. She turned the other direction smiled and blushed. Every day she would ask me to go look for our friend who was doing the song with us.(it was 3 of us) We never looked for him all we did was walk around school and talk to each other. We finished practicing and I went back to not talking to her. Whenever her and I talk it's never me who approaches her. Whenever I'm talking to someone she will just chime in and tease me. We had a big argument during Christmas eve. Winter break is over and we've gone back to small arguments. She always takes my sunglasses off my head. One time I wrapped my arms around her from behind in an attempt to get it. She just kept laughing and giggling while I did this. We went to go out to eat with friends and she chose to sit really far away from me. I had a really deep cut in my arm and she just kept on poking it and pressing on it whenever she was around me. She was standing next to me and I told her to go away and leave me alone and she said "No I like it right here." Why is she acting like this? She knows I still like her. People say she likes me but I don’t believe it. Her cousin told me she doesn't like me and she tells her cousin everything. Her cousin also told me she hates me well at least half of me.
I sort of feel the same in the sense I hate half of her too. I know she probably wants to fix things but what does she want friendship or more? Her cousin also told me that whenever she’s around me she’s always on her guard but neither him nor I know why and she wont tell either of us.