I read lately some hateful comments and insults between users and I find it weird.
Let's say you found your nemesis on Italki and you usually have arguments with him/her. You downvote each other, keep tracking each other movements...
Here's my advice: BE AN ADULT! Just walk away and ignore your hateful other.
Eventually, your nemesis will get tired. If not, just follow the plan.
All right, if you refuse to become enlightened :-)