Believe me, I've done the same in the past with Dad who has AD, and Mum who was looking after him had some major meltdowns. There were times where he just wore her down asking if the poor puss has been fed, over and over because the cat miaows all the time. Mum would get so frustrated and then Dad would come next to her, not knowing how he made her feel, and kiss her and say he loved her. She would stiffen and look very cold, not because she didn't love him, because he had pushed her to her limits without knowing.
Short answer, your OH has probably forgotten, but you're left with anger and guilt. Let it go, you will fly off the handle but often these difficult and aggravating stages pass. Forgive yourself, I maintain dementia is a nuclear problem and we are caught in the fall-out zone.
You're a good person doing a hard and often thankless job because you love, love yourself too.
Stephanie, xxx