Get a life. I don't know man. It's just a game. I can't see how someone would have that big of a problem with anonymous strangers online. If you make an effort in real life to make friends, get a job, get a girlfriend, stay busy, you won't think of league as such a big deal. Maybe start working out. Whenever I play league after I work out, nothing affects me. I just can't be bothered with immature insults when I know I just ran my ass off and worked an 8 hour shift. It's so inconsequential to me because I have more important things to worry about. You know, real life things.
If you continue to put so much focus on video games, you're gonna find yourself depressed. But you won't be too depressed to do anything about it, because you have league as an escape. It's a dangerous spiral. You'll have moments where you feel like a piece of shit and ask yourself "what am I doing with my life?" ...but then you'll load up league of legends and distract yourself from your real problems. So you won't ever do anything about it because you will always have league to fall back on. It's not healthy man. Find something else to live for, and your frustration with league will become silly to you. You'll find yourself having good games, which make you happier, and when you have bad games, you won't rage and get so frustrated. It's a win win. You have to address the problem, not just find solutions that cover it up. Don't just turn your cheek to the underlying depression that results in absolute rage when things don't go your way in a video game.