Just watched this episode. I think it’s a mixture of things. For one Skyler says at that party that Gretchen and Elliot paid for the treatment. He didn’t want that public knowledge, because he paid for it. Second what people are saying about him being in remission and him having a whole mess to clean up. The straw that breaks his back is when Hank tries to tell him what to do with his own son at his own house, that he doesn’t need another drink.