I don't think there's anything you can do to speed up his recovery from his A. I would avoid talking about her and keep your home a relaxed and emotionally safe place for H to be. He sounds like he's still very vulnerable to her, so remain vigilant in your DB efforts.
Do you have any idea what he found in his A that he felt was lacking in your M? Maybe steps towards meeting those emotional needs will leave him feeling less bereft without her...
