Opinions plz! Torn.pissed & annoyed

My bonus baby’s birthday is coming up he lives out of state with his mom, my man mentioned the upcoming day to you saying he wants to fly out . Me and the bm do not get along and in my opinion she still wants him(their son is 5, i adore him and he loves me but his mother definitely tells him negative things about me and he’s hesitant to really be attached to me i can tell, we have been back together 4 years).At the the last birthday party(that i planned the theme & location for)the bm was rude and my mans mother who was also in attendance told me that i was overreacting and that the bm was not obligated to be nice to me. I told my man I dont feel like the events of last year were addressed properly because her behavior was not checked by him , and I dont really wanna go but im not comfortable letting him go alone because 5 months ago the bm was talking about getting back with him and was telling her friends and family because she had a talk with his mother who encouraged her to discuss her lingering feelings since she knew that her son and i were in a rough place and going to counseling .so my question is should i go or stay home?