Don't use it. From your description of the incident and the state of the cell, looks like you've had a non-catastrophic internal short, hence the puffing in the pack. You've probably damaged the plastic insulators and any further vibrations could make that worse.
Fill a bucket with salty water, dump the LiPo in it and leave it for a couple of weeks. That will safely fully discharge it so you can take it to the local recycling centre.
As said above, get one with a hard case. Never run soft-case LiPos in a car as you can see what happens! Personally, I think you were lucky it wasn't worse! HTH
