Why did she betray me?

My bestfriend of 1 year and I moved away for college together.
She had told me she was suicidal and wanted to go away and start a new life with me, and she broke up with her controlling bf. she had no money and her parents weren't helping so I offered to support her until she was stable enough to help me back. I gathered money from my jobs and paid expense. But when we arrived everything went down.
We would fight as she was ungrateful and I had an alcohol addiction, and I was recovering from some trauma. Sometimes she'd slap me or bite me really hard which drew flashbacks on me. I was feeling traumatized from my past and I was struggling with paying her expenses. I overdosed on ecstasy and ended up in the hospital. She broke down and stayed there all night.
After I got released, we started over. She took care of me, fed me, and slept next to me.
Anyway we got in another fight which resulted in her telling me to kill myself. I got drunk and I laid a hand on her. We started hitting each other on the street
She began screaming for help.
I ended up at the cops again. And the uni began a disciplinary hearing against me.
Then we decided that she'll move out and go live with the other friend.

For the next 2 months it was a series of push and pull game.
We sat down to speak once after the police incident. She said "I was in love with you." After a pause, she rushed "as a friend." She wiped my tears and said what's broken can't be fixed and we had to forget each other. I didn't give up. I felt really guilty and I wanted to get her back. One day I made her a surprise lunch with 2 of our friends (boys). They invited her over and she made a scene at first. She sat down eventually, ate, and when it was time to talk, she said she'd never forgive me.
Later that day I saw her sitting alone, crying in the corridor and I sat beside her. She didn't say anything, just leaned her head on me.
A few days later, she b*tched at me and made me cry. The next day, she sits with me and has a casual friendly talk over coffee. She was telling me she was sick at the hospital and she wished it was me to be there beside her, rather than the guy she was with. Then at night fights with me again. We sat talking for a long time, she held my hand and said she loved me so much, that she picked me over her boyfriend twice, but now her heart feels nothing for me anymore.
The next day, she punched me in my chest when she saw me in the elevator. The following day, I had bought her a teddy to apologize with. I kissed her forehead and said I'll never approach her again and I accept that we're done.
2 hours later, she came in the room and saw that I was going out with her friend and she came as well. At the cafe; she was quiet. She got angry when she saw one of the waiters flirting with me and offering me free drinks.

Then we held hands under the table. Before we were about to leave, she told me she felt sick and leaned on me for support. We got a cab, I took her and the other drunk friend to their room and told her I'll bring her some chocolate. I fed her and told her I'll leave bc I had to see my guy friends. She said she's not feeling well and asked my to stay with her. Then she wrapped her hand around my waist and cuddled me onto her bed and spoke to me till she slept. In the morning we woke up together and left the room. Later she thanked me for taking care of her. And after that she started a whole fight where she broke down and accused me of destroying her.
I had gotten drunk and broken a bottle against the wall and was taken to the hospital.

She knew I had my wrist stitched and didn't bother to see me. Instead she sent me some cruel texts saying she knew I spread rumors about her (which I didn't). Few days later I found out some terrible things.

She had told her "boyfriend" about my history of abuse and mental issues, and he proceeded to investigate my past.
She tried to ally herself with the man (my ex bestfriend) who had raped me 3 years ago to extract information out of him (even though she hated him). She called me a wh*re and a sl*t and accused me of wanting it.
Then started spreading it there amongst the boys and calling me manipulative, saying I was using my charm to get under their skin and get to her. With her friend adding rumors that I was bisexual, a psychopath, and obsessed.

She claimed that when I was drunk I tried to sexually abuse her. But what actually happened was, I was drunk yes and I remember kissing her neck. She moaned and pulled me closer to her but then I got aggressive and pushed myself off her and yelled at her.
Even tho the truth was, she used to ask me to come over to her, sneak me over when her parents were asleep and we'd smoke hookah and she'd cuddle me on her bed. Once she acted weird, and said she loved me, leaned in and kissed my nose. I took it as friendly and I kept it to myself.
She also used to send me revealing/sexy videos of herself and again I kept private. Or when she would say she was addicted to me and couldn't live without me.

I couldn't handle it anymore. I defended her in my statement at the disciplinary hearing and even though I won it, I was forced to leave the semester and go back home. The day I travelled, we met up coincidentally and we spoke. She said I ruined everything between us and that we were over. I held her hand and hugged her for the last time and left. However when I was at the airport, she kept calling me. She told me "I'm going back to my ex. Even though he cheated on me, atleast he didn't lay a hand on me. He gave me love and protection which you never did, you only gave me money. Which I'll give you back. You loved yourself more and because of you I hate everyone."
Then she continued to call me at random times just to insult and swear at me. The last conversation we had was her telling me we were toxic for each other.
I haven't heard from her since a week.

Can someone please explain what was the possible cause of her behavior?
And am I wrong in this?
I just miss my bestfriend.