hi aintnosunshine,
im afraid i dont really have any advice to offer. just to say that my dad has always been very depressed and anxious too though wasnt diagnosed until a few years ago and has been awful at working on it so i know what you re talking about. i watch my mum struggle with him all the time and wish i could help her but theres nothing i can do.
just from your son's perspective (and i know you didnt ask about that but just in case your interested) i hope its ok if i just say its so important you explain to your son whats going on with his dad and that it has nothing to do with him. also because the depression might keep his dad from being there for him and being supportive you really need to make sure he gets as much of that from you as possible. i dont mean to add to the pressure you are under. one of the biggest things i wish for my mum is the courage to see that theres only so much she can do and then it really is up to dad to take responsibility himself. you can only do as much as you re capable of. you are not responsible for getting him well or for taking over his responsibilities while he is sick.
i wish you luck, courage, strength and peace for your heart.
biiv