Well, I didn't have an answer when the above happened to me (minus the portal to hell part). After three months in a new town, it turned out my roommate's rent checks had been bouncing, and my landlord never bothered to notify us until he showed up with eviction papers. I worked a job that kept me away for a week at a time, so one day I just came home to find all my possessions boxed up in the garage. It was as simple as that -- for the first time in my life, the sun went down and I had no idea where I was going to sleep. And it was the same for the next night, and the next week, and the next month ...
I had moved to Montana after finishing up my worthless liberal arts degree. I moved in with some cool folks my age and started a six-month contract job. It was an AmeriCorps position with weeklong shifts working in the wilderness, building hiking trails and whatnot, followed by a week off to spend in town. I was halfway through my contract when I found myself homeless. There are people with worse stories, of course -- many homeless are mentally ill, or maybe their parents kicked them out of the house for being gay when they were teenagers -- the point is, the line between where you are now and sleeping in your car is much, much thinner than you think.
Sometimes it isn't so much a "line" as "peeing in your boss's coffee."