Help (Depression)

I’m 14 and my mom has depression due to her divorce with my dad ( 3 years ago). Today is her birthday and so far she has spent the day crying, I guess she’s having one of her episodes. I feel like this happens quite often especially on holidays (Mother’s day, Christmas, her birthday,...). Sometimes I just wish she would get over it and try and stay strong for me because I need my mother. She takes antidepressants but I feel like they aren’t always helping. Sometimes I feel like this is too much for me to handle. Has anyone ever experienced something like this and if so, do you have any advice?