No room for it

So, we had my son's baptism on Sunday, and it went pretty well. We had it at a Catholic church, but my wife has no intention of staying at a place which does not accept our family (aka our future family).
Anyhow, it's getting rather difficult to deal with the in-laws, the direct ones anyway. I thought things weren't going too bad on Sunday, when they came over for a party afterward.
Now, before I tell you what was said, let me explain the relationship I have with my friends. I have a group of great friends, all of whom are very accepting of me. We are all like brothers and sisters. During the course of the party, I sat on my one female friend's lap, and another female friend, and a male friend and I made a sandwich on the couch. It's just how we are. We're all very comfortable with each other, and know that the love we have is sibling, not otherwise.
Well, come Sunday night, my sister-in-law is texting my wife, and tells her how "inappropriate" my behavior was, and how she would never stand for it if she caught her boyfriend sitting on another girl's lap. Well, I'm sorry you have trust issues (major trust issues btw, I wish I was kidding), but that's just the kind of friendship we have.
To sum up what she said, she basically told my wife that she should have been offended and told me to knock it off. Well, my wife didn't like that, and told her off. She hasn't heard from her sister since.
Then, the next morning, she is telling her mom how her sister acted, and her mom said that she and my father-in-law felt the same way. Well, my wife went off on her too, saying that it is our house, and our friends, and they cannot tell us how to act in our home.
I'm just about done with them honestly. You say nasty things about me, treat me like a criminal, and I still treat you like family, I am friendly towards you, I invite you to my home, and this is the thanks I get? Unbelievable. Well, their strikes are running thin if you ask me. If they say the wrong thing, they might never set foot in my house again, and I know how my wife feels about everything. They are stepping on shaky ground.