What can I do?

Hi! My name is blank, and I used to get permanently banned a lot. Over the past year, I've really got my act together. However, my first permanent ban in about a year happened today. It's no excuse, but is definitely a reason for the stress I experienced. Got a good 5 games of INTers, trolls, and some genuinely nice people who were just having bad days. No excuse, I get it, but what can I do to stay calm/sane during these moments? I haven't had a punishment on this account for a good while( couple months ) and this is one of the few times I've let the stress get the better of me. I threw around the word idiot sometimes, and complained, but that's about it. I can post screenshots of chat logs if need be, however there's more games than just the two shown on the reform card where I said some things. Particularly a game where we had a thresh top, vlad support, and the heca and ahri gave up within 5 minutes and wanted to open.

TL;DR Got banned, haven't gotten banned in almost a year. How can I deal with stressful situations, ie people having bad games, trolls, INTers? I genuinely want to get better, and become a better person, but I'm not good with stress, video game or IRL.