I think you are doing the right thing. Keep that up. Tough situation. I hate alienating people but sometimes you have to. It usually aint pretty and I always regret it.
I like everything you wrote except the regret. I have none in regards to this topic. Cling-ons and it's not for me. Sometimes in life there are people you meet and interact with that need to be strangers you use to know.... That was told to me by a very wise man. Age makes a difference and the older you get the less tolerant about stuff like this.