I think it must be an unusual relative or carer of someone with any form of dementia who doesn't sometimes worry, that they are maybe beginning to suffer from the same thing, themselves. I think you need to "cut yourself a little slack" as you are living within a stressful and emotionally demanding situation. I "only" had my mother to deal with when she lived alone and was getting into all sorts of problems, I say "only" but that was bad enough and the worry was following me back home to my own home, waking me in sleep and disturbing just about everything, including my health. Stress and sadness makes us more forgetful, make us make mistakes, do things wrong. I think it is important that you don't heap the worry of your potentially losing your own mind upon to what you are already dealing with, with your husband, day in day out.
Somewhere, amongst everthing else that you are managing here, you need to carve out a little time where you can do something which relaxes you....something kind for yourself. My mother, now in a care home, has always been largely unaware of the extent of her dementia and I sometimes think, what if it is myself or my husband who gets like that. Having been made cruelly aware of the difficulties created by this illness maybe we(and I!) need to ask for the trusted intervention of a relative or close friend(preferably younger and not someone we are living with) to let us know, to alert us, that we might need to go and get checked out....and otherwise leave it at that. In your situation you have enough on your plate.