NO, NO, NO, I would not go.
I would make sure I had all the support here and I would even make sure that if there was any whiff of my dh taking the kids i would ensure their passports were safely stored elsewhere. Not sure i would suggest this though in case he then decides to try it.
You would be very vulnerable there and if you are vulnerable, your kids would be too.
DO NOT GIVE IN TO BLACKMAIL.
Presumably he met you in England, knew you were English, married you here and had agreed to stay here and is now changing his mind. Even if only one of those things was true I would be very suspicious of someone changing their mind like this.
"I am very torn because I believe in equality" Do you really think you are going to get equality there? Are any of your children female? Do you think they will get equality there?
Please donot give in to this man's pressure on some sort of confused feelings of equality. The world is not an equal place for men and women and you will not find equal treatment in Egypt.
Re "...treating both cultures the same and allowing them equal influence and weight in the DC's lives." That is fine if you think both cultures will treat all your kids equally the same and you can give your kids that experience from the safety of Britain.
"I feel I have already bent over backwards to accommodate DH's wishes." then stop bending over backwards. Stop giving in to him. Please get help for your PND and get some assertiveness training too.
"I have told DH's parents our house is an open house to them, even though they are not particularly nice to me and have made it clear they are angry DH married outside of his culture."
You sound like there are so many issues here, really please do not make yourself vulnerable to these people, they will not look after you.
"I asked DH if I refused whether it would be a deal breaker. He said it wouldn't end our marriage but he would feel that I would have "deprived our family of an experience essential to our health, growth and happiness." Which is basically opening things up to lay blame at my door for anything that might go wrong in the future.
What do you think?"
I think fuck that for a game of soldiers. If it is a deal breaker, so be it. I would never move my family to another country I was not happy to live in just to make my husband happy. If he is so worried about his own happiness, then he should have thought of that earlier.
Let him blame you in the future if he chooses. Your marriage sounds very unhappy, no support and lots of emotional blackmail thrown in. Have you thought about talking to women's aid?
If not, if the only issue is his emotional blackmail then I'd say, He asked asked you, you answered him, no. You gave your answer stick to it.
I agree with RandomMess "It's almost as though he's keeping you barefoot and pregnant to manipulate you..."
and
"I'd tell him to move back there and sort himself out, then potentially divorce him if he continues to be so selfish angry."
Please get some help if you need it, for PND and for your husband and your in-laws, who all sounds horrible. Sorry
