wow, it sounds like a lot of stuff is going on. I'm sorry it's so difficult right now.
I think reaching out to a crisis line is a good idea. They can help get through the tougher times sometimes. Also, feel free to keep writing here.
If you are in an area with 211, they can help with connecting you to services that will assist with keeping power, phone, water, etc on. I know I faced a similar situation with having everything cut off and not being able to make rent, and I got several resources from 211 to help get things back on track.
Can you remind your brother that you guys agreed not to do presents this year?
Also, if your brother is diagnosed, can he get additional services? Maybe something to help him secure housing on his own (or at least additional services to make it easier to have him in your home)? Would telling the state that you have an additional person in the home help get more in food stamps? Maybe having him apply for his own? If not that, can he supply some food for the house? Are there any food banks around your area? I used some regularly for the past 4 years because it's so difficult to make ends meet.
I hope you can find some relief from everything, and some support.