Use the positive reinforcement method of treats (what Charlie considers high value, might not be what you consider high value) and having men/boys give to him without looking/touching him until he becomes comfortable around them. These treats only come from these men/boys, never from you. If you hit him for growling at your ex, it could make the situation worse because Charlie will take the approach of your ex to mean getting hit. He could then become more agressive, and the next bite could break skin.
You might also want to ask your ex to not reach over Charlie's head to pet him, if you're able to. He shouldn't be touching/looking at him any more than the other men/boys in your life or those of your children. He should also be giving treats to Charlie, if you feel comfortable asking him to do so. |