Welcome to the forum. What you are experiencing is something that is extremely hard for a person with "normal" health let alone someone that may be experiencing depression.
I understand that you want to be there for the ones you care about and in so many words "want to slay the dragon" but sometimes you have to realize that the beast is to big and that you can only put your own health in danger as well. It is really sad what is happening in your world and there is no magic potion.
I am not sure how old the two of you are but if you are of age have you ever considered moving in together? I am not condoning this, just a suggestion.
The most important thing I can tell you is this, your health is most important!!!! No matter how hard you work, sometimes you must look out for #1
I will say a special prayer for you.