My partners (33M) ex (also the other parent to his child) hates me (32F) for no reason, if you’ve ever been in a similar situation how did you cope?

A couple of months ago I had the first face-to-face moment with my boyfriend’s baby mother after almost 4 years. Based on stories he’s shared, I knew that she was problematic in ways, but was always hopeful that because I never had a conversation with her or have done anything to her personally, that we would at least be able to tolerate each other/co-exist when the moment came. Wrong. For this same reason, I’ve never celebrated him child’s bday on days when she’s around, I would join when he did things involving his biological family. During this moment, we did not know each other would be in the same space. It was a community event thatJ attended with my boyfriend. She felt the need to try & paint a picture that she was more important than I was & was very confrontational, but in a passive way interestingly enough, directing all of his comments toward him. We did end up in an altercation unfortunately & my boyfriend (& his family & close friends who were present) did ultimately take my side which caused her (& her sister who was there) to be even more upset. I’m sad because I’m a very open minded person & although I love him, my ideal situation would be one where if I dated a man who had a child, their mother & I would at least be cordial & have a mutual respect for one another. I’m realizing that will probably never happen because of her immaturity & lack of respect for him & me. I also have a child. Our children are the same age. He doesn’t really care my my child’s dad, but they’re at least able to celebrate my sons bday in the same space for a few hours. Has anyone experienced anything similar?

TL:DR, my boyfriend’s bm dislikes me for no reason. If you’ve ever been in a situation like this, how did you handle it?