Getting mentally harrased by a friend/sister with whom I fought

I have a friend named Ananya Mitra. She was very close to me. So close that we used to hang out together, she was like a close sister to me, she tied rakhi to me. We were so close that jokingly we used to hit each other and everything, like every other brother sister. But she has also been very selfish since long time. Like she does everything for herself only. It feels like she is using me. Now around 5 days ago, she again did something selfish, and I lost my cool, and like we do fight, I went to her home and hit her on the back. To this, she started to hit me and we fought. Then after around 10 minutes, I went to her to say sorry to her, to calm down, and to this she kicked me. And then I also pulled her hair, she hit so hard that I dislocated my shoulder and she scratched my hand with her nails. Now since then, first she started to threaten me that she will complain about me in the college as I hit her, and get me rusticated. So to that I responded that go ahead, but I will also make sure that her career is also destroyed and she also gets rusticated as she also hurt me. Now, then she says that ok she will not complain but I have to stop coming to their house, and I have to apologize to her infront of all the batch, and give her a written apology letter. I'm ignoring this, as this looks like she is doing it to satisfy her ego only. Now she is spreading false information around the college that I hit her, which is not exactly the case. This is mentally torturing me, and feels like she is mentally harrasing me. Please tell me what should I do