You don't know me but/I know you weren't asking for advice but ...
I recognize this feeling. In my case it wasn't the muse going away. It was clinical depression, and it's taken a therapist, a psychiatrist, and a change in my lifestyle to do something about it. I'm still not painting, but I am writing pretty seriously (even though I'm filled with doubt).

It's plainly not a question of ability. Your post is beautifully written--there's no way you've lost your talent.

Good thoughts from me to you.