Letting go of the anger

I've decided to let go of the anger I feel towards my husband for leaving so soon.  You see, I had warned him about his diet and especially about not getting enough sleep.  I specifically told him that you need sleep to rebuild your body and failure to do so ends in death.  He did not listen and find myself angry.
I can't live with this anger.  It's too destructive.  What's done is done.  So, starting today, I've decided to focus on how happy he was in his final days.  He even told me and a friend that he'd never been so happy.  That he had everything he wanted and his future was brighter than every.  It's sort of bittersweet, but I think I'll hang onto the fact that I had something to do with  his happiness.  And that he died happy which is something that all of us want.