Two and a Half Men, Big Bang Theory and Mike and Molly creator Chuck Lorre speaks at the Banff World Media Festival on Tuesday, June 12, 2012. THE CANADIAN PRESS/Bill Graveland

BANFF, Alta. - Even with the success of three hit television comedies, there is one thing that still weighs on the mind of Chuck Lorre — his ugly personal and professional breakup with troubled "Two and a Half Men" star Charlie Sheen.

"It was heartbreaking," the writer-director-producer said in a question-and-answer session at the Banff World Media Festival.

"The guy was my friend and probably had been for eight and a half years and we never had an argument in that time.

"The show ran and it was an amazing machine, then it became this thing and for it to end like that was devastating. I don't know what to say about it except to say I was heartbroken and hurt."

"Two and a Half Men" first aired in 2003. Sheen's ongoing alcohol and drug problems prompted CBS and Warner Bros. to cancel the remainder of the eighth season in February 2011. He entered drug rehabilitation, made disparaging comments about Lorre and was officially fired a month later.

Sheen's character was killed off in the ninth season premiere, "Nice to Meet You, Walden Schmidt." Ashton Kutcher was introduced as Walden Schmidt, an Internet billionaire.

"I'm thrilled we kept it on the air," Lorre said. "In a way, as we were doing this we realized we had to put some closure on the 'Two and a Half Men' that we'd been doing for eight and a half years and then to begin a new series. We knew we were going to be under a microscope.

"I was enamoured with this young man (Kutcher) and still am. He's amazing and a skilled comic actor. It was actually very exciting to do. We would go home at the end of the day 3 1/2 feet off the ground because we were having fun."

There was little development time once Kutcher came on board. He was originally going to be cast as a loose-cannon actor, but Lorre said Kutcher's real-life fascination with the Internet made it a natural choice to switch out the character.

Lorre said he still suffers with constant insecurity even with the continued success of "Two and a Half Men," "Mike and Molly" and "The Big Bang Theory."

He said the initial pilot shot for "Big Bang Theory" was a flop and rejected by CBS.

It did include Jim Parsons (Sheldon) and Johnny Galecki (Leonard) but not Kaley Cuoco (Penny), Simon Helberg (Howard) or Kunal Nayyar (Raj).

"The girl next door was a hard-drinking party girl and a very fine actress but it didn't work at all," said Lorre.

"We learned that these brilliant characters were very vulnerable and the audience didn't want them to be around an antagonistic female regular. They wanted someone nurturing.

"There was a child-like nature to them. Even though they were geniuses you felt this need to protect them."

Even with the three shows he has on the air right now, Lorre said he would "absolutely" be willing to add another if the right opportunity came up.

News from © The Canadian Press, 2012