Irish, I went through a little of that a long time ago, but I stopped it fast. My XW had a short habit of driving up to my house with the OM and sat there and looked around. I put up with it a time or two and she called me one day trying to bait me into a fight. I didn't fight, but I told her that if she came back again, they would both leave feet first. She threatened to call the police on me and I invited her to do so.... I also told her that I didn't care if she called the President, if she came back again, she knew what to expect..... Needless to say, I wasn't bothered by them again. I know some folks will think that is extreme or barbaric, but at some point you have to draw the line with these people.
