it hurts so bad and its all my fault i need help

im fifteen and i recently messed up badly, i started harassing and stalking a friend i met online whos eighteen because he left me because i wasnt mentally well enough and it was effecting his life and at first, i didnt mind his friends ganging up on me about it or him being mean, i liked it at first because it gave me attention but now its it kinda hurts and i know i brought this upon myself but i also know that something happened when he left, i lost all control of my thoughts and impulses and things i did which lead me to my actions and id never experienced that ever before and it was scary and i think its somewhat wearing off but seeing him have a support system who are supportive to him and defending him from me hurts so bad, ive never had a support system, friends, people who would do anything to stick up for me and its all my fault, if i wasnt too sick for him to begin with maybe he couldve been my support system and maybe his friends too but i had to mess it all up because i couldn’t suppress my need for attention from him while we were friends and now im probably going to spend the next few months as an inpatient while he gets everything and i shouldn’t even be upset because its my fault, its all my fault i shouldve found a way to be my own support system and found ways to control my impulsiveness and my urges i hate this so much i just wanna be normal i need someone to talk to me or reply or anything please im so desperate