I wish I had some good advice to give, but I'm afraid I have nothing. :/ I am sorry to hear you're going through this though, it sounds rough. If you feel like he is a danger to himself or others though (including physically harming you), I -believe- you can put him into the hospital against his will. It would likely be met with friction but perhaps it's what he needs.

May I ask how many hours a day he spends on his computer? I have struggled with being addicted to computer games in the past...my first time being at the age of 15 as well.

Welcome to PC! I hope you enjoy your time here.