I think that point of communication is common with relationships. Many people are just afraid of hurting the person they love. From our few counselling sessions we were taught to try to phrase things as
"when you ____, I feel _____, I need ____" that way you aren't saying "you always do ____ and I hate it" (raises hand...I'm kind of guilty of that sometimes)

I'm going to say his response seems pretty normal. Think of it as a can of pop, when you told him about cheating, you shock the can really hard. And while, you aren't telling him anything new, its still extra fizzy and will explode if you open it. That was kind of like the way my brain felt for....a few months. And I was afraid of being shaken again, here I'd sat content in my fridge for 5 years, then out of the blue came this wind that knocked me off my feet.

A lot of people see faithfulness as a core aspect of a relationship, so when that is taken away, they are left questioning everything they thought they knew. It's hard with you being so far apart, but your actions will do a lot more for him than your words.