How can I tell someone I could care less in a nice way?

Someone who screwed me over is trying to save their reputation as one of my friends let them have it verbally. This person sold me a sick dog and did not have anything to say or even try to contact me until my friend let her have it. Now she’s left me a message and I dont have anything nice to say and dont want any further contact. We dont work together and there is no friendship. Need a clever way to tell them to go and pound some sand !