Settle down. The brakes were working. The emergency brake merely needed adjustment.
There has been way too much piling on in this thread. In reality, there was no need for any scolding. The OP has recognized the importance of the issue and has taken it to the mechanic. I suspect that it is a simple problem with the linkage cable.
I will add that in a prior post, I asked why the OP waited so long to take it in. That was actually a dumb question since the answer is obvious. It seemed like it was transmission related. Transmission-related problems get expensive quick. Sometimes, you have to let big dollar things go for a little bit. The reality of the situation is that the problem likely is not going to be hugely expensive, but the OP didn't know that, so she took the normal corse of action and attempted to put off the bad news. We've all done it. Usually, teh problems either doesn't turn out to be as bad as we'd feared or putting it off makes it even more costly.
Human nature is a funny thing.
I don't need to "settle down."
The vehicle experienced this rolling before. When a parked vehicle starts randomly rolling, it goes to the shop immediately. Can't afford to fix it? Tough, either find a way or don't drive the car.
What if my kids happened to be in that parking lot and in the way of a rolling full-size SUV?
What the OP did was negligent. If somebody had been hurt, she would have been liable for negligence and faced a major lawsuit.
A car's owner has the responsibility of making sure her car is safe for the road and others on it. "I can't afford to fix it right now" is never an excuse.