Trouble with fiance or ex fiance

Today my fiance had a fever and wasn't feeling well. We have a baby and his family wanted us to go over. I told him that he shouldn't expose his family because you never know. And he said that his family said it was ok and hes going. I tried to talk to him again but he made his decision. Then he tried taking the baby. I told him I don't feel comfortable because his family doesn't seem to care if others are sick and because what if he gets worse even though he feels better and something happens while he's driving? He told me I can't monopolize the baby and I never do. He always gets the last word. At first we used to compromise but now even if I tell him I'm not comfortable he gets offended and basically says he's going to do it. So idk what got into me but I had this mother instinct and I left. I just drove to the park and didn't get out. I fed the baby a snack and he called me and I calmly let him know that I didn't feel comfortable and he then was angry and tried to get me to say I'm taking my son away from him and I'm not allowing him to see his son. Which is funny because we live together and are engaged and were fine this morning. I told him that wasn't the case, that I am coming back and I just don't feel comfortable with his decision. I believe his mom got there and told him what to say and maybe they recorded me which I don't care because I didn't say anything wrong. He then said that if I don't come back right now that it's over between me and him. And he hung up. I waited until the baby finished his snacks and went back. I got home and he wasn't there. Idk what will happen when he gets back. If his family will come and chew me out or if he will chew me out which I know he will. And tell me to leave. Our name is on the lease and I do have a place to go but obviously I want to take my son with me since he's still breastfeeding. Idk if he can accuse me of abandonment and taking his son away which I don't want that. If all those years and things we went through, he's going to leave me for this. Then I wasn't that important to him. I have respected his decisions and stayed by his side. This time I didn't keep my mouth shut. If I did, and let him go and something happened to him or my son, I wouldn't forgive myself. And if nothing happened. He would just try to say he's sorry or not even say anything and say he's right and make me feel guilty. Either way he's going to give me hell. I made an appointment to get tested and I'm going to find help on what to do in this case if we decide to split up which I think im ready to do so. And what will happen with the apartment but mostly our son.