I'm sorry you are going through that.

"husband cheated on me. it's caused so much pain in our marriage.
i feel like shutting down but i have nowhere really private to do this. so i cannot shut down."

I've been through that and I spent a lot of time crying in my car. Give yourself time to feel your emotions because unfortunately you need to feel them to heal them. It takes a long time to get over the betrayal and he needs to be open to helping you through that. It's difficult.

Has there been any recent abuse or has he gotten help for that behaviour?