Oh you poor thing, you sound so miserable. This is NOT an acceptable way for you to live or him to live. You are both suffering through no fault of your own.
Do seek support from the organisation that support a suffers of this condition - maybe on line if you have problems with finding time alone.
Are you getting access to all the help you can? The CAB can be a good place to start, maybe there is assitance avaliable to you, such as benefits, at home help, resbite care etc. There is no shame in claiming everything you can, your husband's condition is affecting both of you, even if it just means you can get out of the house and have some time in your own.
With regard to the memory issues could you write to your husband? So he has something he can refer to. Maybe that might help? You do not have to live like this, to my knowledge there is nothing in the wedding vows that say you should do something that make you feel uncomfortable and degraded however devoted.
How much support do you have?
Would you consider booking a different type of holiday? Or maybe a holiday for you alone?
I have dealt with neurological conditions and they are incredibly traumatic for both the suffer and family. In some cases it's almost like grieving for someone that is still there is body but not mind or soul.
No your husband didn't ask for this but not did you.
Hth