I dont know what i did wrong and how to move on

This might sound somewhat silly or unserious because of our ages but 4 months and a few days ago my girlfriend (18F) left me (17M) and, while not nearly as bad as before, it digs at me everyday and i have no idea what i could have done differently or if her reasons to leave were even valid.

Initially, i met her online, summer 2025, but she wasnt that far away from me so i gave it a shot and she became my first girlfriend. When i met her irl i realised i was somewhat catfished (she didnt look as good as the pictures to a significant degree) but by then i was attached and loved her anyway so i stayed despite not feeling a lot of physical attraction.

Everything was great, i showered her with love, affection and compliments. For every picture of her she sent me, no matter what, i wrote whole paragraphs complimenting her and expressing how much she mattered to me (longest one was around 5 pages). I remembered every important date, her birthday, namedays, international girlfriend day and any other achivements she got. Despite her living far way, i still managed to send her gifts that i picked out to best match her interests. I spent the vast majority of my free time (and sometimes time that shouldnt be free) talking to her in some way, mostly videocalls. Everything she wanted to do we did, be it videogames be it just talking or whatever else. She found my voice calming so i stayed with her every night and read to her until she fell asleep (one time it took until 4 am) which caused a lot of issues with my sleep schedule and relationship with my parents. Although she didnt do as much, she still reciprocated the love and rememberance, complimenting me a lot (something i really appreciated as i wasnt really used to it) saying she wanted to marry me and have my kids and also doing her best to make me feel happy whenever she could.

Despite all this, things started to change around january, when my already demanding studies got even more serious, leading to me not being able to spend as much time with her as before. Be it willingly or forcefully i had to spend a lot more time dedicated to studying, and even then i still talked to her every single day, texted her at least once when i got to school, lunch and coming home (at around 6 pm) and then called with her until she fell asleep or I was forced to leave ( every day that i didnt absolutely need to study because there was a test next day or something of the sort). Even then, because i couldnt be with her 24/7, she started, accoring to her, having breakdowns worrying about where i was and blaming me for them. I got confused as i explained to her i was with her every moment i could and during school it was dangerous to even text her, but she just got madder as she found issue with the way i phrased my apology saying i should first tell her what she felt was valid and only after give my explanation (which she refered to as excuses) so i changed the way i talked to make her feel better.

As time went on, she kept getting mad at me for the same things and other things that werent under my control, like when i got my phone taken (due to the stricter rules enforced by my parents after seeing how much time i spent on it, and consequently with her) or when i had unexpected events that took my attention from her ( visits to grandparents, doctors appointments etc.). One time, she even got mad at me because, after she said she was going to study for a while and left, i didnt text her, getting even madder when i explained i just didnt want to bother her while she was focusing, and another time when i sent a fitcheck to my friend (while wearing the clothes me and him bought and just arrived to my house so he could see how they fit) because i didnt send it to her first and didnt usually send them to anyone at all including her. Whenever she hurt me i was always quick to forgive and move on, but whenever i made a mistake she remembered it forever, one time she threw one of those questions girls ask their bfs at me (would you rather marry me now or in 10 years) and, being realistic, i said 10 years and she never forgot that and kept bringing it up.

Eventually, a day when i came home at midnight due to a school trip, 15th of april 2026 right in the most demanding time of year (accademically speaking) which she knew about, she sent me a 7 page breakup text citing my "abscence" and lack of support as the main reason why she ended it (note i never stopped doing the things i mentioned in the 3rd paragraph just couldnt do it as often) and, as a minor reason, another mistake of mine she never forgot despite me doing my best to apologize, explain and make it up to her (she mentioned once she had suicidal thoughts because of the pressure she faced from school and i said i supported her and she had me, friends and family who loved her so it was no reason to kill herself as it was too radical and (knowing personally people who were way worse off and survive to this day despite trying to end it all several times) i said i felt it was somewhat disrespectful to the people who have way worse problems) once again, i realised the error of my ways and did my best to rectify what i said.

After she left me, we tried staying friends. She didnt adjust her behaviour tho, she disrespected me every single time we called, still attempted to use me to entertain herself and sometimes even made fun of how i was alone and had no girl to live life with. Most of the humiliation only stopped when i put my foot down and forced her to stop but i still felt like shit. it all culminated around may, a month after she left me, when she started talking about this new guy she was excited at the prospect of liking her, she told me a lot about him knowing it hurt me as it was visible and, frankly, common sense. it made me feel so insecure and hopeless (she knew i was very insecure about my physical appearance as i confessed it to her somewhere in our relationship but didnt seem to remember). One day i just couldnt take the pain anymore, it was hard to breathe, i missed school, tests, important events because of the pain and she stayed just as brutal. Eventually i blocked her on everything and have been in no contact since around mid may. Last i heard of her (from a friend, around a month and a half ago) she failed her entrance to med school and had had already some people ask her out but who "didnt feel right". I remember her everyday and it hurts so much despite everything. I cant even find other girls beautiful i always remember her and then how shes probably with another guy telling him the things i used to love hearing as well as how horrible i was according to her and doing with him everything we shouldve done togheter. The weight on my chest doesnt go away and it just makes me so much more insecure and demotivated to do anything. She was from another country and everytime i hear anything about it the pain intensifies.

How can i ever move on? How do i stop this from happening again? I hate her for all she made me go through but i still love her so much i was ready to spend my life with her.