Katy Perry’s musician ex consumed by jealously over the star’s new romance with British comic Russell Brand.

Gym Class Heroes star Travis McCoy, who dated the “I Kissed A Girl” singer on and off for more than three years, is reportedly green with envy that Katy is now romancing renowned womanizer Brand — the Forgetting Sarah Marshall star has previously admitted to struggles with alcohol and sex addict.

A source blabs to The Mirror: “He’s livid, but getting a sick kick out of the idea their relationship will go under due to Russell’s philandering.”