@lost girl,
I feel very sorry for you.
As an old man having been though this kind of situation, please allow me to share some thoughts with you.
How deep are your feelings to your husband ? Apart from sex, are you happy ? Do you share some interests, passions ? Can you spend hours discussing books, movies, music, politics etc. .
You say your husband masturbates and hides to do it. I like your Idea of spanking him for that. After punishing him, you should tell him: '' You masturbate, that's okay with me if you let me watch you doing it'' or propose him that you masturbate together, hand in hand, or suggest him a handjob or a blowjob instead.
As they say in girly magazines, try to seduce him or, if it does not work, be seducive to other men. Making him jealous could be a way to have him take more care of you.
I think the question is:''Do you agree to a relatively happy life with a man not interested in sex or are you ready to start your life again ?
The choice is in your hands