Van stalls when we put it in reverse and drive

Unfortunately the condition you're describing is the result of a failed torque converter clutch (in the transmission). The converter clutch typically engages at higher speeds, mostly for fuel economy purposes. In situations where the converter clutch gets stuck or stays engaged all the time, the vehicle will act very much like a manual transmission when you fail to push the clutch pedal in when coming to a stop. Normally replacing the torque converter fixes this issue, but based on the symptoms you experienced just prior to this, there's a strong possibility of further internal transmission damage. I would suggest having the vehicle evaluated by a transmission specialist.