Well, it sounds like the conversation went well, however, he does appear to know what to say to keep you hanging just a wee bit longer. Until he actually seeks therapy, I wouldn't hold my breath. They tend to tell us things that we want to hear, but don't always follow through. Actions speak louder than words, so take what he's said w/a grain of salt.
I'm sure he's very happy living in the family home w/all of the stuff and his toys is wonderful for him. He's not the one that was uprooted and he will do everything in his power to remain right where he is. He's really not that concerned about what his son thinks because if he did, he would made sure his child remained in his home. No, your h is more concerned about what his child will think of him and what others will think as well. Why wouldn't your child not think it's because of you and him that "daddy" doesn't want both of you living in the home now? What's to stop your child from thinking this right now? Sit down w/your child and have a chat to see where his thoughts are. It's time to start focusing on him a bit more. The thoughts have probably already been planted w/your move out of the home. Your main concern is your child, but also do not allow your h to manipulate/control you through the child either.
You have a lot to think about. However, if I were in your shoes, I would still return home and also seek out the professional services of a child therapist for your son because he's going to need to speak to someone whether he is living in an apartment or your home.
As for your h...he would either live in the guest room or he would hit the road to discover what life is about. After all, why should he have all of the comforts of home while you are living in an apartment? Isn't he the one that's not happy? Then he should be the one to go out in the world and find that happiness pill on his own, whether it's living in a tent or under a tree...but you and your child should not have to suffer for his crazy making behavior.
Just my 2 cents this morning.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
