Can an uninjured man from an auto-accident sue?

I was involved in an auto accident a year ago and the guy is now suing my wife instead of me. He refused medical treatment at the scene to fire rescue and the sheriff’s office. He told everybody he was fine and needed nothing. His truck had a very minor damage. Now his attorney responds back today saying they want $25,000 or they will sue my wife. He refuses to get any shots or further medical treatment other than pain pills. My 5 year old was in the front seat of my truck which was totaled and he wasn't even injured but this guy is claiming all kinds of injuries. He had no injuries at all after the accident. He was even picking up his kids and laughing and playing with them. Do I have anything to worry about? Why is he suing my wife and does she has anything to worry about?