Just going to get it out my head

Couple days ago got invited to a shower which is it my boyfriend brother wife’s baby shower.i went all the family and friends are there basically ladies.i start to notice this lady sitting in front of me omg it my boyfriend ex....after I went home and like told the bf about the shower and start mentioning about the ex to him and how I thought it wired seeing her there and why did the mother invite both of us there? Am I just overreacting...