Sorry to hear that you have to sell the car. Maybe you'll be able to come back to it in the future.
As for selling the car, check with Mr.Mustang on this forum. He's got plenty of experience. I would recommend some kind of escrow service. I think the one I used a few years back was
www.escrow.com You and the buyer can negotiate who pays their fee, which is fairly minimal. This service helps protect you and the buyer. Best of luck.
Steve