Camila, the guy has some kind of mental disorder. I'm not being dramatic, his behavior is both consistent and extreme enough to be considered a symptom of an underlying mental problem beyond his control.
Quote from CamilaI noticed that he messaged me each minute of the day. Sometimes I just couldn't answer because I have a life and help my family with things at my house most of the time, and then I received messages like "why you don't answer??? Don't you care about me?" I obviously replied saying that that wasn't true I did care about him and I just didn't have time to answer him, he was like this everyday all the day, 24/7. I was getting tired of it. Even when we played online games he just wanted to play with me and only me, and if I refused he would go all depressed like "why don't you play with me?" "your online friends are more important right?".
This is blatant emotional manipulation. Instead of respecting your personal time and who you choose to spend it with, he demanded your undivided attention and punished you whenever he didn't get it.
Quote from CamilaHe created an account here on sp only to send me messages, and see what I do, after a few conversations he said that he would commit suicide if I don't like him, he already tried to, and went to an hospital for not eating or drinking water (yeah he decided to "die" that way)
Do you have proof of this? Because I seriously doubt it's true. If he actually wanted to kill himself he wouldn't choose to do so in the slowest, most painful way possible.
This is blackmail, he's trying to control your emotions and behavior through threats of suicide and refusing to let you control your own life.
Quote from Camilathen he said that he never wanted to see/talk to me again, so I stopped messaging him. After a few days he got all pissed cus I didn't message him, and used really harsh curses in his message.
He realized his previous tactics weren't working and tried something new - he thought if he cut you out of his life, you'd miss him and come crawling back to him. Once he realized it wasn't going to work he got frustrated and took it out on you.
I don't know how you can possibly continue calling this narcissistic, manipulative piece of shit a "nice guy". If he tries pulling this shit again call the police immediately. Until then at least get transferred out of his classes. This is something you need to take control of before he does it for you.