Okay so vent alert. I've invited my younger sister to my baby shower. I at first didn't want her to…

Okay so vent alert.

I've invited my younger sister to my baby shower. I at first didn't want her to be there because we haven't talked in nearly a year because over the fall she started causing a lot of drama and told a boat load of lies about me and our parents. She's a train wreck to be completely honest. But I invited her to be kind and allowed room for us to mend the relationship. She texts me this morning asking me what day in having no the shower. I told her the 16th of may. She says oh well I won't be here because Redbull has asked me to go on a week long trip with the sales team. Not that I am against job conflicts but seriously?!? I'm going to have a baby. She's going to be an aunt for Christ sake. I told her it was her decision. She was like "well I already made the commitment because I thought you planned your shower for a later date." Which is true but I had to change it to make sure my cousin could come (my cousins shower is on the 30th which was when I was going to have mine). I'm so beyond pissed off right now. Like seriously. My sister is going to be an aunt. You'd think she'd make the sacrifices necessary and be all excited about coming to my shower and be grateful that I even invited her. But no. It's the complete opposite. She's still selfish and thinking of herself.

Am I over reacting??