Need advice !!!!!

Okay I have no idea where I should put this but oh well anyway so this is going to be long so sorry in advance but I here is some back story :

3 years ago I was in a very serious relationship with this guy and it ended very badly but we had been together for a very long time. In that time he had given me a STD and towards the end I was treated very badly and definitely mentally abused by him. The break up was very traumatic for me at the time.

Well now .... I am now in a relationship with my boyfriend and last year around this time my boyfriends cousin started dating my ex boyfriend and I let her know that he wasn’t a good guy and all of this but she did not listen. I made a big deal about the entire thing and how I would not be around him but just got told to suck it up by my boyfriends family. I ended up having to spend Christmas with him sitting across the table :/ . They ended up breaking up a little while later thank god . Well now I am 24 weeks pregnant with the same guy I was with a year ago and I just saw on Facebook that my boyfriends cousin is back with my ex AGAIN. I am yet again not knowing how to react. I do not have any romantic feelings for him anymore when I am around or in the presence of him all I want to do is scream because it’s not fair that I have to sit and be around him. I do not think I will be able to do this again like I did so calmly last year. My boyfriend tells me that I have no right to keep his future son away from his family no matter if my ex is there or not. I try to explain to him that I feel betrayed by his family not sticking up for me but he says I should just be able to sit there and coexist because he is just my ex. Will someone please tell me if I am being crazy and should just suck it up or if they are being completely unfair to me and I should stick my ground. Oh and my mother and my side of the family tells me every day that it is not fair to me and that I shouldn’t have to go through this just so they can have play perfect family... so that definitely feeds the fuel to my upset fire. Please give advice I feel crazy right now !

Oh and I forgot to add that we have talked since we broke up and had conversations and every time I told him how I wish he would just stay away from me and that every time I talk to him he is just trying to suck me back in. I think it is easy to say that this person is very toxic and i understand that I should be able to sit and coexist since it has been so long but he isn’t just my ex. He is someone who took advantage of me in every way and I don’t get why that doesn’t click in my boyfriends head that it is more then just me being selfish...