There are many cultures that share small spaces. Sleeping in the same room itself is not psychologically damaging. As I responded before, it is good that you gave him his own space in the room. I would try and find out what he is scared about. Perhaps he is experience some anxiety because of the custody battle with your ex? Whatever the fears are, they are probably temporary. If you and/or your ex-husband are concerned that your son will sleep in your room forever then you
Sorry. I hit reply too early. ....you can always slowly transition your son back to his own room. Wait a bit until he seems less scared and then slowly transition him. You can move the mattress into his room and you can sleep in there the first night, then lay with him until he falls asleep and then if he wakes up in the middle of the night, lay with him again. Then, lay with him for just a few minutes and tell him you will check on him. Gradually help him stay in his room on his own (you can use rewards to help with the transition). Also, I would try to find out what he is scared about and try and address that. And, finally, I would see if there is any way to talk to your ex about it so that he isn't saying anything negative to your son to shame him, which will most likely just increase the chances that your son will want/need to stay in your room. If you are satisfied with these responses please give me positive ratings. Would you like to schedule a follow up to see how things are going and to further discuss how to address specific fears?