You mention your dad has memory problems, but if he apart from these is capable of understanding the situation, dressing and washing himself etc. sit down and discuss what can and should be done with him. Find out what he wants or vizualises, or indeed if he realises that your mother may not recover enough for life to go back to what it was.
Certainly, ask advice from all and every instance that can or should give you it.
Is your father in his own home or in yours? And what exactly does looking after him entail?
There is a vast difference between doing everything for him, and popping in on the way home from work to hear how he is, and you don't say where on the spectrum you are.
You and your father, perhaps your husband as well, need a frank discussion with your mother and her doctors about her prognosis and the sooner the better.
Otherwise, you may well run yourself into the ground before you all reach a satisfactory arrangement. Please, do not run yourself ragged. I know how bad that can become, believe me.
I know too that it can be hard to open your mouth and ask for help, and unfortunately even harder to find the right person or instance to ask, but you, or you all as a family, are going to have to do so, as soon as possible.