Feelings are important, very important. Feelings are not right or wrong. They are personal, they are yours and they are his. You are entitled to your feelings, and he is entitled to his. Susie is totally right, the two of you need to talk. What you each need first is to understand each other's feelings. Then and only they can you work towards a better state.
Gibby's point about diabetes is right on. I developed diabetes about twenty years ago. Shortly after diagnosis, I met with a diabetes educator nurse, my wife was there too. One of the first things the nurse told us was that diabetes would, not might, adversely effect my sexual function. She was right, within five years I was having difficulty getting and keeping an erection. For me, the answer was injections in the penis, these worked for several years, but the time came when the shots had no useful effect. Now, I probably haven't had an erection in six years. But my mouth and fingers still work. And she very much enjoys them.
While he may not be the stud you had years ago, he can still pleasure you, IF HE WANTS TO.
You two need to talk, and decide how much you value each other. The whole person, not just the genitals.