Jodie, the only medicine is from him, being he must help himself. If he continues to help himself then he will get better and the relationship will survive. If not, or if he's not, if he doesn't want to help himself, ie. sitting in self sympathy still, then nothing he does will change much, only scratch away at the surface.

If he wants change, then make him really work hard at it, reward him for his efforts, then push him more to help himself, then backoff and see how he continues.