My DH has treatment resistant depression. He has good days/weeks/months, then his mood just drops again. When he is well, he's kind, funny, loving, affectionate, selfless and generally wonderful. When he's on a low point, he's tired, sleeps a lot, withdraws a lot, struggles with simple social interactions. We have two kids.
He has never ever blamed me or the kids for his mood. He does his best to shield the kids from it and continually shows me that he sees what I do for him, and that he loves me and he's grateful. He feels terrible guilt when he's unwell, because he wants to be a part of the family and to have the energy and ability to do the things he thinks he should be doing with us.
It's not easy to live with sometimes, I do shoulder a burden when he's not well. But I knew all this about him from the start, he was very open and honest with me about his mental health, and he's very proactive about managing it. He sees the GP regularly, is involved in his medication decisions, and actively looks for other ways to feel better. Working helps a lot, and he's gone self employed as it means he can pick and choose when he works, to fit around his health. That again adds a burden, because I have to work full time to make sure we have consistent money coming in. But we've managed to find a balance that works for us. And he has a lot of empathy for me, what I went through with PND, and he was a rock to me in those times because he got what I was dealing with and what I needed.
If he was selfish, or not invested in caring for himself, or not actively seeking help, I wouldn't be able to live with it, and I certainly wouldn't have married him. I know he will have bouts of depression his whole life. But I knew that from the start. And when I said in sickness and in health, I knew what I was committing to. He takes ownership for his own health and behaviour though. That is the critical thing for me.