I never ever block them. I put a great big note on them that lets me know even the smallest beat or comment will set them off and have them spewing money out as quickly as their vulgarities.
I recently was taking constant abuse from a guy in a cash game who was playing every single hand aggressively. For about an hour I folded my blinds to him, I folded
hands that didnt land. I played over passively on purpose. Every hand he had choice words for anyone he beat. I caught aces in first position and limped into his big blind. Like a knew he would, he shoved. I called and took half his stack. Which was twice what he had won from my folds. He was sooooo angry about me trapping him that it was 30 seconds of every curse word i had ever heard and some I think he made up from noises he was making and decided to type those noises. As soon as he paused, I said "its time to leave if you dont want to lose the rest". He shoved his next 3 hands and I took him with AK suited on the 3rd. After another excellent tirade that I was most proud to be the cause of, i suggested he reload because I had not gotten quite enough off of him to take the wife to a nice dinner. He reloaded, I took it all in 5 hands.
The wife and I enjoyed a nice dinner and he is one of many players I hope to see again. You dont have to pay attention to the chat. You can even block it entirely. The best thing to do I have found though, is to smile and know you have a large edge over this person if you can simply control your emotions. This opponent can not.