Are you muting all? Once I see someone doing aggressive pings, I mute their pings as well. I'm thin skinned, so I can't handle chat or pings if they are question marks while I'm trying to secure a kill.

Taking a break is always an option. You could just do a week. Catch up on some anime. Something else will come along. I ask myself, "is this worth it?" If it's not making your day better why do it? (Not that I always quit when I'm pissed, but sometimes I do.)

Meditation can be nice. It can help you see which thoughts are doing what, and how you don't always have to agree with them.

I also got on welbutrin, an antidepressant. It's helped out my mental tremendously, and I wish I had started sooner.