Your husband sounds a lot like the way mine has gotten at times, usually during periods of unemployment (in our case, his business declining precipitously, bringing prolonged "slow" periods where he basically sat on the couch and had his own little pity party). And there were times when I'd get frustrated, we'd talk, he'd be more like his old self for a short time, and then it would all fall right back into the same patterns.
A big part of the problem was that I was talking, but not listening. I never thought to ask him how I could help him get back to better habits, because frankly I was so sick of doing everything that I didn't really have much interest in doing anything else for him. But in the end that's what it took; us working together, rather than me expecting him to figure it out for himself, made all the difference. Simple things - looking over his resume for him, pointing out job opportunities (which was reassuring even though he wasn't ready to give up on his company), specific to-do lists rather than just expecting him to see what needed done, and most of all, putting more of the childcare on him because it reinforced something that he really feels good about at a time when he was focused on the aspect of life that had him feeling bad.
I'm not saying this would work for you. I never had any doubts that I wanted to stay married to DH, and even in the worst times divorce wasn't something I gave much thought to because I've always loved him. Without that, I don't think we'd have made it through. But if you do want to keep trying it is another perspective to consider.Good luck.

Gosh I love this post.
OP, I do think that since you love him and have young children together with him you might want to try something completely and truly *different* for a change - just to know you've tried everything. Doing the same things over and over for 10 years has not worked obviously and in fact has allowed both his bad habites *and* your bad habits to become entrenched. You two have developed deep patterns in your relationship that will take professional help to try and break.
I have experience with both depression and ADHD in our family and honestly either of those could be part of the root cause of your DH's issues. Those two conditions are treatable. So if he's open to treatment and actually pursues it then you might be surprised what a difference it could make.
But in a nutshell I think that if I were you I would try two things:
1. Firmly and lovingly insist that he seek professional help from a doctor. And outline the consequences if he doesn't. Be calm but follow through with those consequences.
2. Try and position myself as his supportive advocate in all of this - his partner - rather than as his adversary. Be the spouse you want him to be. Be on his side. But be firm and have boundaries and insist and follow up on the consequences of his choices.
I wish BOTH of you the best and I wish the best for your kids.