You don't say how long you have been with your partner, but I am not certain I think that makes a difference.
IMO, but this is only my opinion, I think you need to sit down on your own and review your relationship with this man.
He resents your son and didn't like him living with you. Was there a good reason for this? (Did your son treat him nicely or do anything that might have caused this resentment?)
You say your partner cannot see the need to discuss the fact that you are worried about your son and is providing no support for you.
Is he jealous of your children? Jealous when you spend time with others?
What is he doing, may I ask, to make you want to continue the relationship?
Do you own the house you and he are living in, or does he?
If it is your house, tell your son to come home and tell your partner that he can like it or lump it, or leave. If he stays, you expect him to treat your son politely, as long as your son is polite to him.
If it is his house, or a joint property, go to your son and come back when he is back at work.