My girlfriend broke up with me. I really want to kill myself. I know that I fucked up. And i know that nobody else would endure me as long as she did. I always started arguments out of the blue. I felt so alone even though I know all the stuff that she did.

- She really loved me. Or still loves me. That's something we both don't know.
But I know what she did for me. (it was a long-distance relationship, so we couldn't even meet sadly)
- She always was so happy when we did stuff together. Everybody realised that. The way she talked with me. Her voice. The way she sang my name. I could always ask her to talk with me and she would immediately stop whatever she was doing and start to talk with me. And have a call with me that lasts several hours. We had those almost every single day.
- She always believed in me. Much much more than I do. I have really big problems, self-esteem issues and self-hate. I could give her 100 reasons why I should kill myself and she gave me 100 reasons why I shouldn't. She spent so many hours just talking with me about my depression. And even though I still don't think of me as good as she want me to, I realise that I improved. Only because of her. Because of all the nice stuff she said to me about me. She doesn't think that I am stupid or useless. 
- She did so much for me, even without me asking her. She spent so much time explaining me stuff. And I never really thanked her. English isn't my first language and she always explained me the same mistakes I do over and over again. I could always ask her computer science related stuff and she is always willing to give me an answer.

I always imagined a life with her. Having a family with her. Raising our kids. I can't stop to think about how lovely it would be to stand up with her every single morning, having her in my arms. And going to bed together every evening, snuggling with her. Cooking for our future family. Doing everything for her to make her life as nice as possible. I really wanna travel with her. But in the end I fucked up. So many times. And she always gave me one more chance until yesterday. I really want one more chance and change now. But it's too late now. And I will probably never get one more chance. She says that she still loves me. Kinda. And I would do everything to change. I will give my best now. I know the stuff that I did wrong. Or felt wrong. But it is so hard to change. To stop thinking the way. I just think that it is maybe the best way to tell the stuff that I did wrong. (I had a meeting in a "hospital"-thingy last month. I talked with a psychologist. The next appointment at the hospital will be next week on Monday (8th of January). I will not see the psychologist again but I will see a psychiatrist (I hope I don't mix up some terms) and we will talk about the possibility of taking anti depressants. After that I will get another appointment at the psychologist again and then both the psychologist and psychiatrist will figure something out together (It's not only about BPD but it is also about the depression and transgender stuff)

- I was kinda controlling her. I always made a drama when she did stuff without me (the fact that there is a time difference of 9 hours between us also didn't help at all). I was so upset when she did stuff with somebody else. I should be happy if she has other friends she is able to spend time with. It's not only about me. But I feel forgotten so easily. I know that I shouldn't. I know that I have no right to own a person. And I don't want to own her. But I can't get rid of the idea that she replaced me with somebody else. I always think that I want to spend 24/7 with the person I love. And I demand the same. But I know that this is not possible. I ask for way too much. I ask for something nobody would be able to provide. I should give her enough time for herself and others. She also has her own life. Her own family. Her own friends. 
What can I do to stop having those thoughts? To not feel replaced and unloved?

- I always overreacted. Over really small things. In general. This is kinda related to the first question. But I always think in extremes. Zero or One. Love or Hate. Together or Separated. It's just really hard for me to come up with a different solution. For example she doesn't respond to me. Maybe she was even online after I wrote something to her but she didn't see the message. I know her long enough to know that She just doesn't pay attention to messages as much as other people do. The obvious and most likely answer is that she just didn't see the message. But my fucking brain thinks that this is only the start of her leaving me. But in the end it was my reaction to it.
What can I do to not overreact? To not make a drama out of really small things?

- She also said that she couldn't deal with the fact that I hate myself that much. I "study" computer science for 1,5 years already. With "study" i mean that I stopped to go to the university after half a year. I was in the university last year only one time i think? I am a neet. And I think that I am useless. I only take the free money from the government and I can't give anything back to the society. And I think that I am really stupid. I am 21 and I wasn't able to succeed in anything so far. I didn't even pass the final exams in school. And now I'm sitting in front of my computer 24/7. The obvious answer to improve is that I have to change something. That I should try to find a job. But I tried. And every company so far said that they are not interested in me. That's probably because I will be a dropout from uni and my grades are really really bad. So they will just take somebody who is more qualified for the job. She isn't the first one who told me that I have to change.
What can I do to think better about myself? To not hate me anymore?

- I never really told her how I felt until an argument already escalated. And then it was already too late. I tried to keep all those bad thoughts in me. And then i started to give her ten accusations at the same time. And this obviously didn't help at all. I was just too much. It turned from "i feel really shitty" to "and then its this and this and this" in only a second. I am always scared that if I don't hold all those thoughts in me she will leave me. But then I do the opposite and it's even worse than everything I could imagine.
what is the correct thing to do? How can I talk about problems? Should I talk about problems even when I know that I am the problem?

tldr; my gf broke up with me. she says that she still "loves" me. I wanna improve right now. I am about to start to see a psychologist and psychiatrist. But I wanna improve now already. those are prob the worst problems that our relationship had bc of me:
- I controlled her. I was upset when she did stuff with other people. what can i do to give her enough time for herself?
- I always overreacted. I made a drama out of really silly things. How can I stop with that?
- I hate myself way too much. How can I stop with that?
- I never really communicated with her about how I felt until I blew up and made an argument. How can I stop with that? What is the correct way to react/communicate?

I really hope that somebody reads the thread and is able to give me some skills.