I have a pretty difficult relationship with my SIL.
Here's one story:
For DC's birthday in the summer, we were planning on having several friends and family members over at the house. I mentioned casually to SIL that we'll be doing BBQ and she asks, "Oh, what are you BBQing?" So, I told her we were planning on cooking up sausages and hot dogs (in addition to soda, chips, potato salad, green salad, etc.). So, SIL goes on a rant, "No one in the family likes sausage! You really need to make something that everyone will eat! You should make chicken."
So, trying to be nice, I changed my menu and bought some chicken thighs and legs at a good price. I looked at chicken breasts, but it was pretty pricey for the 25 or so people we were expecting to feed. Of course, later that day, SIL called to check up on me, "Did you get chicken?" And I told her that I had gotten a good price on some thighs and legs. And she went off again, this time about how her family only eats chicken breast and no one would like legs or thighs... and, "Oh, I'll just have to bring steaks for my family!"
I was

! After all, this was a kid's birthday party at 2 p.m., not even at a meal time. And there would be no way to fit 3-4 steaks on our grill while DH was grilling up chicken. Not to mention how rude it would be for some guests to eat steak in front of our other friends and family who wouldn't be offered any.
So, I discussed it with DH and then called SIL to let her know that if she didn't want to eat what we served, she didn't have to come. She didn't say much back to me, but I knew there would be heck to pay later.
Well, the day of the birthday party, after waiting an hour past the start time of the party and not seeing any sign of SIL, BIL or their kids, we started the pinata. I planned on filling a few extra baggies for SIL's kids in case they came late. Well, about half way through the pinata, SIL's kids came running down the hill to the pinata and one of the boys fell and scraped up his knee. I later found out that SIL yelled at MIL, "How could you start without us? It's all your fault that my son got hurt!"
Then, SIL proceeded to hold court indoors next to the buffet table, pouting and making snide comments about the food and party.
Our friends seemed to have fun, the food and party were a big hit with everyone else, but SIL really managed to drag down the family.
Honestly, I'm learning to be very careful with what I say to SIL. I'm learning that she isn't my friend and that I can't trust her.
