Im So Fed Up. Ugh!

Ok so me and my boyfriend have been together for a while(3 years) and just last year i found out his sister doesnt like me. So she has been really petty. I had put a post on social media how im not going to keep committing to a relationship where every thing is half way done. And she decides to send it to him and tell him that its not the first time i said something bad about him. Honestly im sick and tired of his family. First they tell him our 2 year is old is not his because my son is practically my twin. Then they start things between me and his other sons mother. And now his sister. I've had run-ins with her before this. We were at a family gathering(his) i didnt want to be there but he wanted mw there so I couldn't say no cause om thinking maybe everyone will act like adults * I was wrong about that* So they invited his ex from years ago and she started saying things like She could have him if she wanted and all sorts of bull crap. And his sister was just laughing saying that it made her whole week because the girl made those comments. My boyfriend didnt defend me in fact when I got heated and start to argue back he told me i was over reacting. Im so done you can stick a fork in me. Idc because we have a kid together I want out of this relationship. If i had the option of never speaking to him again i would but unfortunately we share a child so i have to keep communicating but he isnt just going to want to co-parent.