^ I didn’t think about the situation from that perspective… Mc12IT is right. Your husband will tells others that you walked out on the marriage and took away your son from him. He’ll try to emotionally blackmail your son in the future.
Of course he’s going to take care of your physical needs, he’s a guy and he’s married to you. He has his needs too! If he didn’t, he’d cheat on you or become a celibate (which is unlikely). Does he turn to you for emotional support?- like when he’s stressed out at work or when there’s an illness or death in the family? It sounds horrible… but maybe if something really serious like those happen, he’ll turn to you for emotional support and realize your value. 
Regarding more kids… just wait on it. You already are a mother, focus on your one child. How old is your son? Have your in-laws asked you if you’re planning on having another child? And your SIL… did she get married? If your SIL is now married, I don’t understand why your husband is still holding grudges. It is very possible that your in-laws are encouraging him, saying that they endured “baysati” due to you.
Divorce is an option, but just remember that it’s something you can’t undo when it’s done.