I have done this but not after doing a lot of soul searching. I tried different avenues of trying to resolve the problem, even speaking frankly to them about it but to no avail. It took years for me to reach the point where I said: for the sake of my sanity I need to break contact with this person on a permanent basis.
I tried to imagine how it would feel without them in my life, how this would impact me i.e. could I live with this decision. I made my choice, explained to them why and broke contact.
I cannot reiterate enough that this was done with a lot of soul searching, as this obviously will have an impact not only on yourself but on the other person or persons associated with them and you.
You need to be aware of the repercussion of your decision, the ripple effects it might cause and be ok to live with them. It has been about 10 years now and I do not regret the decision.
I have done this to a couple of people for similar reasons. Over time, they really began to dislike some of my other friends, and eventually started going on vendettas and nasty, aggressive smear campaigns against them in places where they couldn't defend themselves. When I tried to defend the victims, I became their next victim. I dropped them like a hot potato after that, and shut them out of my life forever. Should have done so long before I did in all of the instances though. I haven't looked back since.
I'm learning not to get involved with people who play these nasty games in the first place, and am wary of red flags and warning signs.
i have done this a number of times. i have been a prey to leeches who seemed to involuntarily claim ownership of me as some sort of validating force in their lives. like dark angel i tried hard to resolve this particular problem of mine with these individuals, talking directly to the person about the issues and expectations that i had. i tried to let associations die through neglect but these sorts of people have been persistent and followed me relentlessly, either as though everything was fine or demanding that i treat them the way things used to be, long after the point at which i thought it must seem abundantly clear to anyone that things were not going to work. i found it impossible to deal with at that point and usually resolved the situation by deliberately smashing the relationship to bits. i haven't ultimately regretted the outcome in any case but i don't want to go through any of that again or put anyone through that again and i'm very careful of who i let into my life and to what extent.
i have very old and dear friends but still sometimes in thinking about these things i have felt sad and lonely and questioned my ability to sustain relationships.