AITA for skipping my dad's retirement party after my girlfriend invited her ex?

My girlfriend told me her ex was coming to my dad’s retirement party whether I liked it or not because I needed to “stop acting insecure.” I didn’t argue. I updated my RSVP and left town for the weekend. By dessert, she was sitting with my family without me, trying to explain why I’d skipped my own dad’s celebration. ---------------🦖D - Stories🦖--------------- #reddit #stories #redditstories