The Smashing Pumpkins rocker couldn't understand the media storm which grew around his relationship with the singer-and-actress, and insists reports of them dating were far from accurate.
He said: "The stuff that I've seen doesn't have any bearing to the reality that I'm in. It's like being in a cartoon. It has nothing to do with what's really going on or how I feel."
He claims he was approached by Jessica to work on the theme song for her latest TV series 'The Price of Beauty'.
He added to US TV show 'Access Hollywood': "I ended up writing part of the theme song. She asked me to help her out. It has a little bit of an alternative rock edge, but it's still very poppy."
Reports of Billy and Jessica dating first surfaced in November last year, though by January they were said to have split.
Jessica - who was previously married to Nick Lachey and more recently romanced American footballer Tony Romo and womanising musician John Mayer - recently revealed she wants her next husband to be an "artistic man".
She said: "My next husband will be an artistic man. It will show you the colours of my character, the person that I fall in love with next.
"I don't even have a type! I don't have a physical type. I have an emotional type."