I simply don't put up with it and my family, what family I have left anyway, doesn't cross me. None of them think Im an asshole and love me, but they all no not to push me. I established this 'no bullshit' attitude many, many years ago and nobody crosses it, now. On the occasion it may, I put my foot down and it's respected.
It's hard to comment on your predicament without walking in your shoes or at least being involved more directly. The only thing I can really say is to talk to them and tell them the problem. I cant tell you how to be more direct/covincing, etc. in a post. I can tell you that once you make it clear to them how this makes you feel and how it's affecting your relationship with them and with others and they still cross that boundry, then you have to stick with your guns. If that means telling them next time you don't want them coming to visit or if that means literally kicking them out of the house, then so be it. They'll have nobody to blame but themselves. If they truly love you and your family, they'll get it eventually and learn to respect you the way they should. If not, suck it up, and know that sometimes this shit happens and live with the knowledge that you tried your best, amicably and with the best intentions and wash your hands if it's going to cause this many problems. It's ok not to get along with your parents. It's not like you get to choose them.