Chapter 7 is personal bankruptcy.
The deficiency caused by the repo is now unsecured debt and can be wiped out right alone with the cc's.
On the car you want to keep, you may just be able to keep making the payments. Reaffirm means you want to legally maintain the current debtor creditor relationsship. If you don't make the payments, they may repo the car and come after you for the balance. If you don't reaffirm, just keep making payments, you can give up the car anytime post bk and not be liable for a deficiency.
Most bk lawyers give free initial consultations. Talk with a couple and get all of your options explained.