Husband's midlife crisis.

My husband is 40 and I'm 38. He has been acting out recently and trying to behave like a 20 year old constantly going out drinking and whining about being 40. We have a 16 month old and my 12 year old stepson and I don't like how he comes home late and only wants to spend time with younger co-workers. He just told me he is having midlife crisis and it's bothering me. Anyone else go through this and survive? How get through this and work through our differences of how we see our responsibilities?