Okay so I will keep it as short as my heart will make it

I recently got a girlfriend and when I got her my now ex bff seemed cool with her. Well this challenge that she made happened where we could not have any form of comuntication at all with eachother, in that time she called my girlfriend a bitch and I got angry and extended the challenge. I confronted her about it later when we ended the challenge and she said I call her boyfriend names. Let me explain the relationship between me and her boyfriend. We are close, he calls me names and I call him names. We check up on eachother and we both have an end goal of making my ex bff happy. So he doesn't mind and I don't mind and she has never brought it up to me ever until now.

Then we went to gym. There is me, my ex bff, and 5 other friends in our gym class. We were walking the track but the gym teacher is lazy so everyone mostly sits on the bleachers while I am the only one who walks the track because I like to walk alone and listen to music. Well one of my friends came over and I knew this was important because they never bother me on the track. The first words out her mouth was "(Ex bff's name) is talking shit about you" Now I had this happen to me about every year of school from every bff I had every year. I get a new one to replace the memories of the last one, she was the one who lasted the longest going 2 years.

I was already making arrangements in my mind of who I trust and then my friend says "She is also talking shit about {My girlfriend's name}" Now I was fuming. I had also just gotten out of a pretty bad relationship with a guy as and my girlfriend made me pretty happy about myself and she's done so much for me so I was kinda protective. Also my girlfriend is sensitive as I said earlier so this angered me so much. My friend went back and I kept walking, well stomping around the track. I got only about a quarter of the track down when my friend came back angry and said "I can't take it! She is saying your girlfriend is a bitch and is making her so fucking mean!" {Sorry for profanity, just quoting what she exactly said}. I huffed and was ready to go over there until my friend said "(friend name 1) amd (friend name 2) is also talking joining in and they are all just talking shit" So I gave up that idea and was angry

In the end I cut of all of them who was included. Now my ex bff gave me notes, which were mostly guilt trips and attempts to get me back. I ignored them all and just write back that she needs to move on. When guilt trips didn't work she started telling me that I can never replace her. Let's just say on a very bad day I snapped and told her she was to replace a different ex bff so she can never say I won't replace her.

Well we decided to stop talking fully, even though I was trying that she made it official. Well I noticed some things that are happening. She writes my name all over her arm, with my name are little things like "I will love you no matter how much you hate me" "I can't leave I just won't". Not just her arms either, her arms, ankles, legs, and shoulders. She writes notes about me, I know about this because one of my friends who is friends with her came to me and told me and as far as he remembers there are some like "Did you ever love me?" "Was it ever real?". It has gotten to the point strangers that I don't know have came to me and asked am I okay and is she harrasing me in any way. Even a teacher that hasus both for two diffrent subjects came to me and asked has she done anything to me. Then days ago she sent this:

This whole time even her boyfriend knows she did wrong and we are fine. He checks up with me sometimes and sees how am I doing. But I do have a friend who thinks I should say sorry for cutting her off and making her depressed. I am just so done! Just, what do ya'll think is her end goal in this whole situation?