Am I wrong for hesitating to send my coworker the tip?

So I'm a dog groomer and yesterday my coworker groomed one of my regulars dog. I guess nobody told my client that her dog was getting groomed by somone else and the client assumed I did their dog because they cash apped me the tip for the groom. I'm debating sending the tip to my coworker or keeping it since my coworker never paid me back for the food I ordered them last month but it feels wrong. I could not say anything and no one would ever know but I'd feel guilty or I could tell my coworker and send the money to her. The ironic thing is its the about the exact amount of money my coworker owes me for the food I ordered for her weeks ago. Am I wrong for thinking this? It feels like it...