It sounds very difficult for you Stormchaser, I'm really sorry.
I wonder if you have considered if your husband is maybe suffering some form of social anxiety rather than just being overworked and tired? It does sound like he works incredible hours but if he is as intelligent as you sound then he will understand that life is for living and no matter how bad the economy is money still isn't everything. What is the point in struggling to make ends meet if you're unhappy?
Free sources of entertainment (friends, long walks, fresh air) are a vital part of everyday life and it sounds like your man is very shut off from entertainment of any sort. I don't doubt he enjoys his models, I could do maths till the cows come home but I will eventually get depressed because it's not healthy to do sole pursuits for such long periods of time. We do all need people to some degree even if, for me anyway, it's only a handful of people, where others need many.
Is it possible that seeing you enjoying some other activity will spur him on to give it a go with you? Could you find an allotment, or maybe look after a vegetable patch for an old person who is no longer able but takes pride in their garden? Your husband could join you and you could relearn the art of conversation.
(and help please, what does "DH" mean? I see it used a lot but it isn't a term we use over here!)
This might sound decidedly odd, BUT, could you and your husband actually downsize your accommodation? This would leave you with lower bills to meet, hopefully help with some of the financial stress, and maybe even give you more money for activities. Much as we all take pride in our homes, putting more money than need be into where we live can be a lose-lose situation if it stops us being able to afford to see outside those 4 walls. Could you relocate to nearer your husband's work so he wastes less time on commuting. It's amazing what we have all come to accept as just "part of life" that can fairly easily be resolved. I no longer look for work that, when push came to shove, I couldn't walk to (I'm happy to do a very fast 1hr walk).
Your husband may be worried about losing his job, but is he doing a job that meets his dreams? Is there something else he could do that he would find more fulfilling?
Happiness isn't selfish, it is so important and a life without it is somewhat wasted. Yes, we have to find happiness where we can (to some degree) but there is also nothing wrong with making huge alterations to our lives if it makes life a lot easier for us and our loved ones.
Could you (together) volunteer to assist adults with literacy and numeracy problems? Could you volunteer to offer respite to people who care for a relative with learning difficulties? Such pursuits would let you meet some fascinating people.
Anyway, point of my post is that maybe your husband is behaving the way he is because he can no longer see what he is missing, maybe he is mildly depressed (very possible with a different working situation). We assume he should be able to recall and see what he is missing out on with you, but if there is any level of depression then everything (even that which went before) will be viewed through the depression so he won't feel he is missing out.
Just a thought, but always worth investigating other causes.
Random x