What do I do with this?

Ok so I’m a 24 years old mom of an almost 2 year old boy. And I’m with with his dad and we are almost to 5 years being together but in having a problem right now. For context I work for my mom on babysitting my three little sisters so she can work. And I really wanted to help because my little brother had passed away not to long before now. And my bf works with his dad in his dad’s business so during Monday to Friday he doesn’t really see me or his son but he has time during the weekend. And even then doesn’t make time but complains he doesn’t have time with his son. And while drunk he told me “this is why I don’t want u going to ur moms, because I don’t get to see my baby as much. If I knew this would happen I would have stayed with my other son’s mother.” Which he has another son with another woman which is now 9. And personally I felt my heart sink to the ground. And before then he called me while at work me taking care of 4 kids in total including my son and he heard my son crying which was cause I had smacked his hand when he was messing with my mothers electric washer and pushing buttons and I had told him to stop already 4 times and he had turn it on. But when his dad heard him he told me “you better not be hitting him for everything” which for me I took as in wow he must think I’m a bad mom when I’m with my son 24/7. I know how he is and acts and when he has tantrums and when he was messing with the washer he was cranky already and hadn’t had a nap so it made him more sensitive to when I hit him. But at the end of the day u barely see ur son when we live in the same house and ur telling me how to discipline my son. It’s not like I ever leave a mark on him or something for him to tell me that if not I would have understood. But then now it’s Christmas and had get presents for everyone so the kids fits 3 each and I got 2 for my bf which in total was over 100 just for him and I didn’t even get a present at all and when I asked him to check his presents he said no I don’t want too and he was drunk then and wakes the next day to drink even more. I don’t know what to do anymore. And in this relationship there has been cheating on his part a lot and still are together because I want my son to have his father when I didn’t. What do I do? Also idk why nowadays he doesn’t respond to my messages on sc unless it’s be 2 hours and if I’m lucky maybe an hour and I know he gets on sc cause he messages his friends there and to ask them to come over he asks them there. I know he is ignoring me and just a second ago out son woke up crying and so he was extra cranky and didn’t want his dad all on him and so he starts crying when he dad keeps touching him all and he is pushing him away and his dad gets annoyed and says he is being a cry baby and before closing the door to our room he says “just like you” and he was drunk by then and it’s only 2 in the afternoon.