If the charge went through, then the card is obviously valid and they got the money. I would not be comfortable sending a pic of the card, but they already have all the info they need if they were going to scam you. Ask them if providing the security number on the back of the card is good enough. That security code is a way of showing you have the physical card. The phrase, "Cancel the order and refund my money" may make them more workable. If not, call your card company and request a charge back as they won't deliver the goods.
A pic of the card "could" be used to make copies of it...but not likely as people with the equipment and skills to do that already know what each bank and companies cards look like.
