There isn't a whole lot Chris can do on his own when Barb dies. He has no real friends, no money, is despised by his relatives, is facing legal issues, and has to deal with a horder's nest. That's a lot for anyone to deal with. For Chris, it's practically apocalyptic.
Another thing I've yet to see anyone mention is the pets. Remember how Chris once said he and Barb couldn't leave them alone in the house or they'd start throwing shitfits? That's not gonna get better when Barb dies. At the very least, those pets need to go to a shelter where they'll likely have to be put down, even if Chris does manage to only wind up on probation. As horrible of a pet owner as he is, I don't think he'll handle having to get rid of his pets so they can be sent to the proverbial farm very well. Especially when said needle is compounded by the death of his mother.
Unless there's a particularly generous Kiwi who comes across a lot of money and wants to head down to Buttfuck Nowhere, Virginia for a few months and hire a crew to empty his house and keep him on suicide watch; this'll probably be the worst moment of Chris' life.