AITA for not wanting to go to my MILs Mother’s Day dinner

My husband asked what I wanted to do for mothers day and I said nothing I want to sit in bed all day watch Netflix and I want him to just pick up sushi I don’t want to do anything I want one day to myself to do literally nothing. His parents asked if he had the day off he said no but he’s gonna call out sick. I don’t know if they asked if we had plans or what he’s saying he doesn’t remember but they decided to do Mother’s Day dinner at their house at 5:30. I was just with my sister in laws and I told them I don’t know if I’m gonna go I didn’t want to do anything for Mother’s Day and my sister in law (she doesn’t have kids) said that’s rude you’re not gonna celebrate my mom for Mother’s Day I said it’s my Mother’s Day as well and I had plans to be in bed and do nothing?? Keep in mind I’m at their house every other day I see them ALL the time god forbid I don’t want to go hang out with them on Mother’s Day from 5pm till my son’s bedtime. Now if I don’t go and my husband and son don’t go then I’m the asshole for keeping him away from his mom for Mother’s Day. But then if I tell him to go with my son then I’m gonna have to go pickup and eat my food alone. My husband does not see the big deal and he thinks this whole thing is funny which makes me equally pissed at him.