It sounds like he's suffering from clinical depression (the clothes, the mess). Does he have any history of depression or addiction in the past, or in his family?
Do you think if you presented it carefully (as in, "I know you're leaving, but I've also noticed all these signs of clinical depression, and I'm concerned for you. Can I make an appointment for you with your family doctor?").
You need to be careful not to sound like you're trying to keep him there.
Meanwhile - what are you doing to change things up for you? Do you feel safe enough to leave your kids with him for the evening while you go out with girlfriends? Dress up nice and go out. Let him sit at home wondering what you're doing for a change. Get a new hairdo, buy some pretty lingerie, do something surprising. Take up a new hobby. Stretch your wings.
Right now, in his depressed state, he's like a wolf with its leg in a trap - he'll gnaw off his leg to get out. He doesn't realize you're not the source of his pain. Start living your most interesting life, shake it up a bit and he may start wondering if he should stick around and join you in that new life.
