Katy Perry undergoing hypnotherapy to get over John Mayer

London: Pop star Katy Perry is reportedly having hypnotherapy to get over former boyfriend John Mayer. The `Roar` hitmaker was apparently devastated when her two-year romance to the singer ended in February amid claims that he had cheated on her. `Katy was devastated when they broke up. They had talked about marriage and she seemed to think he was a changed man, so she is beyond gutted. `But Katy is a firm believer in alternative therapies and she wants to wipe him from her life for good, so she decided to see a hypnotherapist. She wants to retrain her brain to prevent John coming back. She doesn`t want to find him attractive anymore,` a source said. The `Prism` singer, who was previously married to Russell Brand, has split with the `Gravity` hitmaker twice before, but this time she is determined the relationship is over for good.