Hey there Ruqaya! This is a bad situation youre in. I am sorry that you are going through this. If only there was anything that I could do… As sad as it is I cannot help much. Maybe what you need is to consult a psychologist. A kids psychologist even better. Tell them how you feel, and how your son feels. Then act upon what they tell you. That would be your best bet to actually help him without hurting him or his psychology!
At the mean time something else needs to be done before that. If what your son is saying is true you need to tell this to your ex. He deserves to know over all. I think you should even notify the police… I can’t stand somebody hitting a child. Please take care dear. God bless you!