You can't make her understand, that's the problem, . Even those who suffer don't tend to know the exact reason why they're suffering. You said so in your post you can't do chores because you have mental issues, but can you decipher that further? Maybe if you can get down deep you'll be able to move forward. . If you can't, then all you can do is your best.

Don't refer to her as a nag. It sounds so negative. She's a not a nag because she expects/hopes her husband can pick up a dish or two. I'm sure she envisioned a very different life than the one you're providing her, but "in sickness and in health," am I right? She's doing the best she can the same way you and and unfortunately it all starts with YOU. As soon as you start doing more the "nagging" will stop. Until then, this is your life.