That's so sad!! Don't think he was always thinking this throughout your long marriage - if he really believed this he would have brought it up sometime else in the last 50 years, he wouldn't have married you or circumcised your son either. I think it's the disease causing personality changes.
So sad, losing your husband like this. But at least you can know that your husband as he was, was not an anti-Semite, it doesn't need to poison your beautiful memories. Although it doesn't stop how painful his current behaviour is or how wrong.
Just so sad in so many ways.