Advise to prevent yourself from full-on tilting and flaming?

When I was a child, my psychologist told me that whatever makes you angry will make you less angry when you share it with someone. Since I just had one of the tilties, saltiest and most horrible games of my life and I don't know anyone who'd give a damn about it, I just thought that I'd write about it in the Boards.

So I just had a game of Urgot Toplane, which is one of the champions I enjoy the most. As soon as the enemy saw that, they were most likely Pre, they decided to camp me, kill me whenever I came to lane ( they didn't really give a damn about turrets either ) and Spam Emotes to disrespect me, saying things like "Urgot OP" etc. to piss me off. They did not really break the Summoner's Code, stomping and taunting is not forbidden as long as it's not directly insulting but I just cracked. I was really bored and frustated to begin with when I went into the game, and these sadistic pieces of shit just took advantage of that and amused themselves over me failing hard and being frustrated. I started to flame them and call them all kinds of things. I know, this is really wrong and I should have just let it happen and stayed civilized but I couldn't control myself as much as I wanted to.

My question is, how do you prevent that? I keep trying to calm myself down in such situations yet I have not found a way to totally prevent me from tiliting and becoming a lowly, whiny keyboard warrior.