I remember seeing a weird animation in the early 80’s when i was a kid. It looked like a late 60’s/ early 70’s film. The movie first starts out as live action. The main character is a man who’s a writer that’s in love with this blonde nightclub singer. The love is unrequited. I can’t remember if she is murdered or he just finally breaks and commits suicide. The film becomes animated at this point. He is reincarnated as a cockroach and she’s now a white cat.  I remember the  roach running around trying to keep her out of trouble. I think she’s still a jazz singer, but for cats or something. The memory that sticks in my mind the most is a scene where the cat does a jazzy skat version of a line from Romeo and Juliet. ” Romeo, Romeo. Where forth art thou Romeo. Deny your name…”