I'm sorry that your situation is what it is, but you can't take your situation and generalize that everyone's family will react in the same way. Mine supported me during my very long battle for approval, and I don't think my situation was unusual.

I do think the government figures many people who are disabled and applying for SSDI can and will work when forced with dire financial consequences like homelessness.

You need to ask your siblings for help if you haven't. If they say no (or already have) than you need to exhaust whatever resources are available to you locally. Perhaps one would allow you to move in with them? Is it embarrassing and humbling for someone that has always been self reliant? Yes. But you have to do, what you have to do, to survive.

I started the Catch 22 thread awhile back for those facing situations like yours. There are resources out there, you just need to hunt them down.