I now have a lawn chair and a baseball bat with a "free to good home" sign next to it.
My FIL and his wife stepped over that thin line of civility and are no longer welcome in my house. I'm sure the neighbors heard me screaming "Get out of my house and never come back!"3 blocks away. 16 years of pent up anger and a horrible week of frustration finally burst through after they crossed the line.
I don't have the answer for dealing with our elderly parents/in-laws who make things so miserable. What I do know after this week is that my family and sanity are more important than being walked over out of my misguided "respect" to extended family. They chose to do behave horribly all week. I chose to not put up with it in my house. I feel like a huge burden has been lifted off of my chest and I can move on without guilt.