Silent husband

My husband and I have been together almost 4 years and our biggest issue is that he's completely silent when we have an argument. I'm always careful to not show how mad I am and to really ask him about his feelings or what he thinks and he never says anything! Sometimes he says "I don't know what you want me to say" but most of the time he's completely silent like he's ignoring me. This weekend I found out he has a porn addiction he's been hiding from me and I'm completely devastated. Every night while I'm putting our toddler to sleep he watches porn in the other room. All he has said is that he's sorry and when I try to talk about it he's silent. I can't rebuild our relationship by myself and he won't go to counseling with me. I really need advice. I know he loves me but it's like he just shuts down when we have any kind of serious conversation or anything about emotions. 
And no I don't need opinions about pornography and how great it is in your relationship. That's not helpful. Thank you!