First of all, sorry for your trouble, OP - it must have been a terrible shock. But. Your post has made me really cross on behalf of all the people I know who are on minimum wage and earn fuck all despite working loads of hours. Do you realise how lucky you are overall? You have a husband who is capable of earning £65k.
Yes, he's lost his job and there aren't any at that rate locally, but he is capable of earning that amount. What if his job was freelance, or zero hours, or under /at minimum wage?
It's usually pointless to say 'But there are so many people much worse off!', but in this case it's true. Your combined (current and possible) income is over £70,000 a year - most couples in the UK would kill for that.
Your husband clearly has a good skillset in a sector that pays well. So your options as I see it are:
1 - sell the house. Fuck the negative equity - it's a debt you'll have to manage over time. Get advice from a charity about payments you can afford. No-one's going to come and throw you both in jail if you don't pay the equity off in full immediately.
Rent your next house, until any debts - if there will be any - are paid off. Work out how long it will take to pay off any negative equity and stay in rented accommodation until then.
Give your husband a break re the £65k and your 'lifestyle'. Ffs I know families on under £20k. You keep going on about your lifestyle and your mortgage - you know you can just... not buy into all that? If there are no jobs at that rate where you are, then your husband takes a job at a lesser rate, or you move. It really is that simple.
2 - stay in the house for your 'lifestyle'; get stressed because you can't pay for it; lose house anyway.
You are in a hugely advantageous position. Obviously it doesn't feel like that now. But you are in a partnership where the two of you can bring in over £70,000 a year. Seriously, I work with families who would kill for that, who are working all the hours offered, becoming ill with stress and worry... and still only bringing in a quarter of what you and your husband could make in a year.
You will be OK. You're one of the lucky ones who can claw their way back up from a huge setback like this. Good luck.
(I would however want to know why my husband lost his job and if it were gross misconduct... that could be a dealbreaker.)