I've had an extremely negative experience with someone on facebook. I did in fact end up un-friending them. However, I later learned that it's possible to exclude their posts from my news feed without un-friending them, so I re-friended them and did that instead. I was really just tired of seeing all the crap that they were posting, I don't think I stopped caring about them as a person. I don't talk to them, especially about politics, though. I'm not in any way qualified to judge, but IMO you are handling the situation extremely well. Kudos.