Did I Kill My Transmission the Way I Was Driving? (Automatic)

“I am posting this here for Diane I. DeBellevue.”

My son purchased a 09 Chevy Trailblazer approximately six months ago. It has over 150000 miles on it when he bought it. The car seemed to run very well and he has not had any problems with it. He kept up with the fluids etc. I was driving it one afternoon on some errands when the car just did not feel right for some reason. Taking off from a traffic light it would not move. I called him told him the problem and he had me put it in different gears (it is an automatic) in order to get it home which was only a few blocks. The next day we took it to the mechanic and he checked it out. He told my son that the transmission was shot and needed to be replaced. He also told him that who ever was driving at the time – it was there fault that the transmission went out. How can this be possible. I have been driving for over 40years and have never had anything like this happen. Or is it possible? I was not at the mechanic to hear any of this. Now my son expects me to dish out $2700.00 for  a new transmission. Is my son just pulling a guilt trip on me or could he have been told this. I am retired and live on a fixed income. Opinions PLEASE!!!