How can I stop of being angry after every single game?

So... I just wanted to play a game and have fun but after I made 3 deaths my temmates started flaming me and insulting me, well I couldn't let them talk like that so I just went in base and left the game for a while(10-15min). When I came back they wanted to report me because I stayed afk(but they made me feel bad...).I know it is bad having an afk player in the game but I really couldn't resist and I know that I could mute them but this is happening in most of the games that I'm playing. Always I have to see people who judges their temmates... Where's the old community where Lol wasn't almost full of toxic players? I think I'm going to take a break from Lol because I'm sick to be nervous every game. I hope you understood me and if you have some solutions of what can I do I'll be glad to hear them.