Strategy i use to remain calm when my team is flaming/irritating me
Get the last word, and then mute whoever is bothering you.
It feels really good because YOU CANT BE HURT, IRRITATED, OR TRIGGERED BY WHAT YOU CANT SEE, and you dont get that lingering feeling inside you for the rest of the match where it's like "i NEED to say this" since you already got the "last word." Lastly, you can now get back to playing the game and not have to worry about constantly typing to keep your sanity levels up.
Just make sure your "last word(s)" are not something that you can get punished for. For example, saying "you're shit and should uninstall" is very incriminating. However, saying "i dont need to take this from a 3/10 ahri" (i just needed a champ name example please dont hate me for saying ahri it doesnt mean anything) and then muting them is a very good strategy to cooling down and getting back to playing the game.