How to become less toxic
"Fake it 'til you make it."
There are other ways, but this one is simple and relies on a psychological mechanism that everyone has. You see, the human brain is intrinsically wired on an action/reward system: anything you use is strengthened, anything you don't use withers away.
What this means is that if you fake it, if you get outplayed, get angry, but then lie and force yourself to write "good job, that was a wonderful play!" in all chat, eventually you'll actually mean those words.
The lie will become true, because that's just how the human brain works.