The fact that you are asking for some perspective is a really big step. And while advice from others can provide some new avenues to experiment with, this is very much an internal journey that you are going to have to solve yourself.
The first step to do that is to ask yourself exploratory questions around your league play. Most importantly, keep asking yourself follow up questions until you can't answer then anymore! Once you do, pause and give that unanswered some thought over time. It might take hours, or days, or weeks, or even months to answer that question - just be sure to give yourself time to process and fully understand it.
I might not be doing a great job explaining this to you, so this is kind of how my internal dialogue went when I try to figure this out myself:
Why am I getting angry at my teammates?
Because I want them to take the game as seriously as I do.
Why does it make you angry that they might not be trying as hard as you are?
Because I want to win, and if they aren't they aren't trying as hard as I am, it makes winning that much harder
Why do you want to win?
Because I want to climb the ladder.
Why do you want to climb the ladder?
Because I want to accomplish my goals in League
Why do you want to accomplish a goal in League?
I don't know. Because it will make me feel more accomplished as a person?
^ This was the last question that had stumped me. Your questions and answers will obviously be different, but for me, when I hit this question, I realized that I was relying pretty heavily on league to deliver a feeling of accomplishment, because in my real life, I wasn't necessarily experiencing much of that for myself.
Reaching this conclusion helped me understand why I was so emotionally invested in League, and it's helped me to have a different perspective on the game. I still care about playing my best, and I still care about challenging myself and learning, but I get a lot less hung up on losses or feeding teammates. If I am playing this game for fun and a sense of accomplishment, I can't tie that to the performance of my teammates - that's always going to lead to outbursts and arguments. I have my moments like everyone else, but learning to just keep my focus isolated on myself has helped overall. Ultimately I have to accept that some games are just going to be a throw, and there's not much that you can do about it.
Your pursuit of these answers will likely be different, but hopefully this creates a frame of something you can try yourself. Good luck dude.
