Crazy ex (insane if you ask me)

So about 4 months ago i got together with a girl through mutuals that lives close to me (about an hour away) and at first she seemed to really like me and so we got together and was being really flirty for about a week and a half. We decided to meet up for a date and when the time came i was really nervous to not mess it up but i fortunately did not mess up and she seemed to really like me and the second she got on the bus home she said she already missed me and so i thought of the date as a success. About 2 days after the date i sent a message her asking how she is and when the next time we can hang out again is. She said she wasn't completely sure about it and i said i totally get that and she should just let me know when she can. We continued to message back but the weird thing was that after the date her energy completely changed from being like "Omg! I love you so much and i'll never leave you!" to "yeah ok fine ig lol" and i had no idea why she did that and asked her about it just to get "idk" as a reply. A day later when i got out of school i checked my phone and saw i got a message from her and the moment i clicked onto it everything just fell apart. "Hey i know we haven't dated for that long but i think its best if we break up. Bye!". And just like that everything was gone. I didn't take the breakup that deep as i thought i would but what really bothered me was that she didn't say why she wanted to break up, just a simple bye and no explanation? I saw she had blocked me almost everywhere but i still had her phone number so i decided to text her there (spoiler: bad idea) so i tried my best to ask what i did wrong and at least why it didn't work out. She chose to not answer the same day but when i woke up i saw i got a message. "You fucking stalker. I'm taking this to my mom and she's gonna tell the police". I got really scared and apologized but she just said its too late. So i got really worried about what will happen next but i thought it was best to not contact her anymore and let it go. So i stopped completely and i think about almost a month passed away before she messaged me back. She tried to ask for forgiveness and said she misses me but i know the same things was gonna happen again so i rejected her and moved on again. I guess that made her mad (not really) but what she did was always finding new ways of contacting me which over time got really annoying. So i kept rejecting her but in a nice way. I guess that made her take a different approach and she asked if we could be friends and i said yes (bad idea) and so we talked on call with her friends (which are really nice btw) but then i brought up that i got a girlfriend (i lied just to make her get off me a little more) which after i said that made her really mad, sad and jealous and so in her anger she blocked me AGAIN. And what a surprise, after like 3 days she added me back again and now i was starting to get really mad at her. Welp, what a surprise... I told one of her friends that i was going to the cinema in like a week to watch the new fnaf movie and i guess they told her im going there. Im not really sure if it was intended by her or not but what a surprise, she's going to the same cinema, same movie, same time. So then i got really disappointed. She asked if i really was going to the same cinema and i said yes and then she said she's bringing her brother there (who is 16 and im 14 if yall didn't know) and so i got scared because she's still mad at me and so i thought: "What if she tells her brother that im going there and she tells him to find me and beat me up". So i asked her: "So are you bringing your brother to find me or something?" she replies with something like: "Nah but good idea" so i ask "So you want your brother to beat me up?" She replied with: "uh.. yeah kinda". After that i blocked her and started to think if i really should go to the cinema but since this situation has come so far i decided to tell my mom about all this and she seemed to really understand and showed sympathy for me. When i brought up the cinema and what she said to me and that i really didn't want to go even that we already had brought tickets, she made me go with her at last. When the day came to watch the movie i was really stressed for something to happen but when i actually came there, i only saw her and her brother like twice before the movie and after the movie and fortunately she and her brother didn't do shit to me. So i took that as a win and went home happy. (Thanks to my mom for making me go). So about a week or two passes and now its like a day before new years and surprise surprise, she unblocked me and added me again. I asked what she wants but she said she had gotten over me and surprisingly had a boyfriend. She asked if we could try to be friends again (not really but all the signs was there) and so we started chatting lightly again but then while we was talking over text she said she once newly threatened someone newly with a knife but then she says she's not crazy. Like who in their right mind would do that?! So as a joke ofc because we was joking while talking i set my status on discord to ""I once threatened someone with a knife but im not crazy" B***H WHAT DO YOU MEAN YOU'RE NOT CRAZY"". Then i said to her: "look at my status lmaooo" and she replied with "Look at my status then" so then i looked at it and it said: "FUCK YOU I KNOW WHERE YOU LIVE IM GONNA THREATENED YOU NEXT" and after this i texted her a bit more before blocking her. Now i don't know if she's super pissed or not but im just gonna assume that because of her past behavior. Then i started thinking back to when we was together and i remember she once said on call that she always walks around with a knife and she vapes, smokes, drinks alcohol and SHE'S ONLY 13?!!! So then i started to get concerned for my safety. Especially because i was gonna be home for 1-2 days. (at the time posting this i am home alone with all my doors and windows locked) So since she knows my address and she is that crazy to maybe show up at my door with a knife im really scared if she's actually gonna do it now or somewhere in the future. 

So yeah i don't know if anyone is gonna even read all this slop but if you do then thanks for reading. Feel free to give me some tips on what i should do or if something like this has happened to you before.