My sons step mom called me selfish

My son sees his dad every weekend however his dad has been coming here because my son had his gallbladder removed Thursday. My son ig normally babysits his twin sisters on weekends when he's with his dad but he's been laid up in bed. His step mom called and said my ex said my son wasn't gonna be there this weekend. I said yeah he had surgery. She said she really needs him and if can come by Friday at least for him to babysit. I said no. She's saying he would have had over a week to heal so why can't he. We went back and forth and she said if she can have a C-section and delivery twins at 40 and go back to work a week later a 15 year old can after a minor surgery. She then asked what if she brings the twins here for him to watch and I said no. Not while he's healing. Even his dad isn't expecting him to come over. She then said that since in a selfish bitch my son can't come over anymore. I may or may not have called her a fucking cunt. Besides the point. I don't think I did anything wrong.

I didn't call her a cunt until she called me a bitch. I tried being an adult and explaining over and over again why I'm giving him time to heal. Plus it's not his job to babysit HER kids. She didn't even check up on him or care that he had surgery.