NC incase outing and hope I don't sound too petty. For my ds's birthday decided to go to the zoo for the day. I invited my parents so to be fair we also invited DH's parents (mil, step fil, fil and step mil), and DH's 2 siblings and his brothers fiance. I will be providing the food (either picnic or food at restaurant zoo and cake) but made it clear it was pay your own ticket. No obligation to attend just join if you want to. Just found out that Sil has invited her boyfriend that I have never met as well as DH's aunt and cousin without asking us first. I didn't want DH's aunt to join because frankly she is a bit nasty and a loud mouthed bully. Example we invited her to my ds's christening and she called us tight with the food (we provided an £8 pound a head buffet at a fairly naice pub). She has insulted one of my hobbies calling it something for geeky losers. Basically she just ruins the atmosphere for me. No doubt she would come and say we are tight because we haven't paid for the zoo tickets.
AIBU to think you should ask if it's okay to invite someone? And to be really annoyed at Sil? We invited people months ago and Mil has just let slip that Sil has invited them. Birthday is next weekend. Would it be petty to just cancel (we haven't bought our tickets yet thankfully) and just do something at home and not invite Sil? Or is that too petty?