My brother is destroyed and I have no idea how to help

My brothers fiance and baby passed away last month due to complications during birth. He has just died on the inside and I don't know how to help. He has had depression in the passed and I'm afraid for his mental health. I thought about offering for him to stay with me for a little bit just to get him out of that house. I've been over there a few times and his house is disgusting. He completely stopped cleaning and has let so much trash and plates and stuff build up. He has roaches now and he has never had roaches. I told him he's not living healthy and his fiance wouldn't want him living like this but he just gets upset at me for bringing up his house. He can't live like that. I know he's hurting but to sit and wallow in your own filth fixes nothing. Any advice on how to help someone who is grieving?