My Husband's Depression is Ruining Our Marriage

I don’t know what to do. My husband isn’t the person he was a week ago. He isn’t loving and caring and understanding. He’s angry and bitter and always tired. I know he’s depressed. He knows he’s depressed. He won’t see anyone or talk to anyone about it. I can’t tell if the way he’s talking to me and the way he’s acting is a product of that depression. He never does anything to help himself and I’m tired of acting like his mother instead of his wife. I’m tired of the way he behaves with our son and yes I have talked to him about it many many times. He always promised he’s going to change that he’s going to do better and he never does. I’m sick of it. I love him to death but I can’t keep going around in these circles. He needs help.