Depression is ruining my marriage

My husband and I have been married for four years, we got two baby girls, 2 yo and 10months. I have always suffered from depression but no one really knew it. I talked about it to my husband before we got married but he told we would overcome it together. It’s not always that I’m feeling depressed but lets say once a month and if its really bad then every week I’ll feel like I hate my life and I don’t really want to live anymore.

Fast forward to yesterday my husband told me that he was tired, it’s getting harder to help me overcome my depression, he feels useless and is afraid it could affect our daughters. I told him that I wouldn’t want to be selfish, I can let him find someone else. But I love him and this is making me feel worse😢