Gasketboy-
I think the answer is obvious - your girlfriend, knowing how much that car meant to you, should make up the difference.
After all, she was driving it and she should make out real well from the lawsuit she is going to bring against the owners of the Hummer...so there will be enough funds to do this.
If this was my car and my girlfriend crashed it - no matter who was at fault - I would feel terrible. (Explaining it to my wife would be the worst part, probably) I have always felt better crashing my own stuff.
Pat