Congratulations on the reduction of needed medication. It’s nice when we see our healthy choices paying off.
Your wife is in crisis, confused and depressed.
You’re not sure she believes you - don’t sweat it. She’s not even sure she believes herself. Back and forth she’ll wavier and ping pong about. One moment she cares about your health, the next she won’t. She’ll worry the car battery will die, help with housework, then go back into the tunnel and be seemly uncaring again.
Keep doing your own thing. She needs space and time. She is trying to figure her stuff out. Remember this is about her, not you.
When she does something nice like telling you about the interior light she shut off - thank her and agree that she saved the battery from going dead.
When she doesn’t believe why you have Viagra - “I’m sorry you feel that way, but I’m telling you the truth”. Validate her concern, and you can mention that you are telling her the truth. She may listen, she may not; either way you need not explain nor defend too often. That just leads to arguing, and you cannot change her mind, only she can.
You are doing well.
DnJ
Feelings are fleeting. Be better, not bitter. Love the person, forgive the sin.