Not wanting to see family

My cousin and her family are in town after someone passing away. I’m currently 9 weeks and just returned to work after my summer break. I’m exhausted and I don’t want to see family. I know it sounds bad. They are having dinner at my mother’s house tonight but I was told last minute of this on top of that I have a prenatal appointment tonight that I will not miss or reschedule. So they want to know if I have time on Monday and honestly I just don’t want to see family. It would only be my cousin and my mom which can get annoying because they like to treat me as though I’m a child that I don’t know any better about life. Meanwhile I’m the only one of the three who’s gotten her shit together in life. I have a career, a wonderful husband, great in laws and soon to be mom of two can’t say the same for them. Am I being awful? Idk. But help me with excuses.