Some kind of mental disorder? ADD/ADHD? Bipolar? Anxiety? Personality Disorder?

Hello. So I'm an 18 year old male (turning 19 this august) So, Everything started to change when I was around 15-16 years old. I'd never had a girlfriend really before. And then I met this girl online and we started to go out. Long story short, our relationship became really bad. I treated her like a princess. I even sent her flowers to her, while she was at her school. She always tried to make me jealous and always wanted to play games like "Hey, I'm going to the movies with Austin" And I'd get pissed because what girl, who is in a committed relationship, goes to the movies with another guy. Not only that, but she would always say "He was staring at my boobs the whole time haha" which would piss me off more. So I would play her game. I would try and make her jealous. We would tear each other apart. Every single day I became anxious and was afraid she'd make me jealous. (because whenever she did, I would get extremely depressed.) Then she started asking about my Best friend eric, and finally she asked for his number, and I said we'd exchange numbers. I asked for her friends and she said "oh, she doesn't have a phone) A teenager in this day and age with no phone. it was a load of BS. I ended up giving her his number and she would hardly text me, and would text him. I finally freaked out and she said "the reason I wanted his number was so I could arrange for airplane tickets to get there to see you!" I asked eric if that was true, and he said that she never mentioned anything like that. Finally her and I fought and she broke up with me, then got with him. She then broke up with me and went out with my other CAUTION: IF YOU ARE HOMOPHOBIC, STOP READING. Anyway, she broke up with him and went after my ex, Blake. At that point. I was contemplating suicide. I ran into my closet with a knife and my mom chased me. It wasn't a good time. I talked to my ex and asked if she'd sent nudes to him, and he said that she did. Funny thing is. I asked her if she'd sent nudes to them when they were going out, and she said no. So she lied to me. I dumped her for a girl who was a family friends of my dads. her name was Malori We went out for a little bit, but we were caught texting "stuff" to each other, and I wasn't allowed to talk to her ever again. I went into a spiral of depression and suicidal thoughts. I would get moody and angry. My friend Jordyn comforted me, and I finally kissed her. She would regularly come over, and we would make out. I sort of used her to help me get through ****, but then I grew really attached to her and was falling for her. I didn't want to have to choose between Malori and Jordyn, so I called my friend Graydon and told him I was going to commit suicide. He told me he was going to come over, and I hear a knock on the door. I open it to find him and his mom there. his mom said that she could either call my step dad from work or call the cops. I ended up getting with Jordyn. But I was still a little nervous and anxious, because she had been with so many guys, and I was afraid she'd cheat on me. I treated her like a queen and our relationship went up and down. I always was anxious, horny, anxious, horny, jealous, anxious, angry, depressed, all the time. I still am! and we've been dating for 2 years! It's not even her. she makes me so happy! but it's weird, we were having sex, and I asked about her friend with benefit and how big his thing was. she said it was big, but that she always thought of me when they had sex. which I thought was kinky and it turned me on, but then I felt like depressed. I don't know. I didn't want to mention him again, because I didn't want to show that I was kneeling to him. I wanted to show that I didn't care about him, and that I was dominate. Sorry, I know that sounds pessimistic. Sometimes I'll randomly get angry, and put on some Nirvana, and grab a knife and start stabbing a computer chair, and then kick my door in. I just feel so angry. sometimes i'll sing really loud (almost scream) until my throat hurts. At school, I was the weird, loner. I hated everyone at my school. Actually I was caught using my phone during class and this girl stared at me. I hated when everyone stared at me in class. I felt the anger, anxiety building. I called her a stupid ***** and slammed the door to the classroom open and left. But anyway, I still get really angry and anxious. It's weird. sometimes I'll have a really high self esteem and think I'm good looking, feel hyper, but that'll die down just as quickly as it came. Also my step dad and I don't really have a good relationship. He was a jock when he was a teenager, and I'm kind of a, I don't know. Stoner? Like I do smoke weed occasionally, but I mean, I have that sort of style. The ripped Jeans, the band shirts, the music I listen to (ex. Nirvana, Pink Floyd, etc.) Anyway sorry for the drama everyone haha

Regardless if there is MI and what it could be, does seem like the behavior that results from inner turmoil and rage is something to truly consider resolving. It's not something that just goes away on its own. Nothing that one grows out of without addressing the root causes. And it's something that can push others away, that might not want to be pushed away.
It does sound compounded by tension in your home. Is your biological father a presence in your life? Sometimes it takes the non custodial parents support to offset the personality differences between the child and stepparent.

Please don't hurt yourself, you are young and have your whole life left-there are alot of fish in the sea too, i would dump this girl fast. i mean the one who went out with your friend. please see a doc and t too if possible you need to talk out you aggressions and feelings. good luck

Oh we are broken up. Its been along time. I've been with a new girl for about 2 years now.

Do you have a therapist? That's the best way to get a handle on the stuff that's going on and together you can figure out if there's an MI or just anger issues.