I agree with SilverTrees about the importance of communicating with your son. Only your son can tell you how he feels and what would be better for him. Perhaps he can't tell that directly but gradually through a process of small chats where you open up with him (without saying more than he is ready for) and he feels able to open up with you.

Perhaps ask other adult friends for support so that you can talk to your son in a receptive rather than an too-emotional or too-distant manner.

I also think that the most important thing for children is to know that they have a HOME, rather than a series of temporary accommodations. The biggest harm that I've seen done to children was in the second/ third stage after the divorce when children deal with their parents having new partners: where children are passed between two new families. Their parents used the children to express jealousy, one-up, compete with, or attack the other parent. I think that it's a priority for children to have a HOME even if that means compromise for each parent's emotional and relational lives. You can find ways to give children stability and to let them know that their needs are important. For example, one friend and her second husband maintain separate living spaces for their children from previous marriages, until the children are grown. It's their way of saying that children get choices too.

That's the point where children can be completely destabalised.