The first thing you'll need to do is take the car to a very good diagnostic shop to find out what's wrong. It'll be nearly impossible to figure out without a scan tool and a good technician to sort out what's happening and why. Once you've established what the problem is, you can determine potential damage if not repaired and whether you'd rather repair it or not worry about it.
It's possible you have an issue with the transmission, transmission control module, or throtte position sensor, to name a few of the many possibilities.