You have spoken the appropriate words to your son. But if you fear going back to your husband, I would be concerned. You cannot change your husbands ways..only your ways. When you mentioned that you were finally able to break the cycle, what exactly were you referring to? Has your husband stopped being abusive? Possible on going marriage counseling or individual counseling/therapy may assist you and your husband. Your husband may seem to have changed simply to "win" you back. He may have been jealous of the untrue fact that you had a relationship with your male friend. If you do return to your husband, he may act in a loving and positive way but the abusive behavior may soon return. It will take much more than your husband simply saying that he is lonely to change. For your mental and physical health, I would seek professional assistance before recommitting to the relationship. Also, you can receive assistance in what specifically to say to your son because your husband has put your son in the middle of this adult situation.
I hope that this has helped. If you need further assistance, please inquire. Please ACCEPT so that I may be compensated for my efforts. Thank you.