How much space would you give your husband

My husband locked himself away 2 days ago. We were sitting on the bed. I was making formula for the baby and he was on his phone. Looked shocked, dropped his phone, started crying and went to his room. I picked up his phone and an old foster sister of his sent him a link to a news thing about a 15 year old boy who had been murdered by his parents. TW for graphics!

But he was dismembered. I was so confused by I found out from this old foster sister that they were both in a foster home with this boy when they were teens and he was 7. They both also found out about a month late so missed the funeral. My husband called into work the last 2 days. I asked my mom for advice on how to help him and she wasn't very sympathetic and said he hadn't seen the kid in 8 years so he shouldn't be moping around like that. I cried reading that and I don't know him at ALL! I Just want to know how much space I should give him before I try to talk to him about it. Our son is asking why daddy is sad and I'm not sure how to explain this to a 6 year old.