I don't have much to add except get as much information as possible about what the specific ramifications of each choice would be, financially and in terms of being able to sell. As in, "if we take an 8 month holiday and we can't sell the house, our monthly payment will increase by 187 pounds." Or, "if we take an 8 month holiday it will extend the life of our mortgage by an additional 5 years and we will end up paying an additional 18,000 pounds" or whatever it is. I am totally making up these numbers. Also... "if we can rent the house, it will cover all of our mortgage, or 85% of it, or we will actually turn a profit" or whatever.
I wish there was a way he didn't have to "hear it from you" that the house probably won't sell in 8 months. Maybe you could arrange to meet with a realtor and him with the goal of having the REALTOR explain that to him?
I also think it would be REALLY helpful for you to meet with a lawyer to discuss how you should be protecting yourself. It *seems* that even though H is not taking any steps towards D, he is trying to unload your joint assets. Don't let him F--- you over!!! But you don't have to do that before you meet with H. Because you don't have to actually decide on anything at the meeting.
When you're giving him bad news I would try to keep the tone light and objective... not defensive. Like you're saying "these muffins are blueberry, not cranberry" instead of "our house will not sell in 8 months" "[are you out of your mind??]"
Just remember... stay cool and you don't have to agree to anything at that point in time!!! Keep it light and show him your beautiful fun and delightful self!!!
I hope you feel so much better... and that you're getting lots of rest!!
