Jessica SimpsonJessica SimpsonBreaking up is hard.

Even harder? Seeing your ex with a new flame.

Jessica Simpson has admitted it hurt seeing her ex-husband Nick Lachey start dating MTV VJ Vanessa Minnillo within weeks of their separation.

She revealed all in the March edition of US Elle magazine:

"Oh, it hurt me. Two or three weeks later? Yeah, I'd say it kind of hurt me."

The couple divorced in December 2005 after three years of marriage, which were documented in the MTV show Newlyweds.

Jessica revealed about the programme: "I didn't twist his arm. I didn't say, 'I'm going to leave you if we don't do it.'

"I'm happy I did the show. I'm happy I was married. I'm happy that he was in my life. I have no regrets. Not one."

Vanessa Minnillo and Nick LacheyNick and Vanessa celebrating New Year's EveDivorce aside, Jessica is still in contact with Nick: "Mm-hmmm. He's so much a part of my life, how could I not be?

"Any guy that's going to be with me from this day forward has to understand that."

So, what's really going on with Jessica and singer John Mayer?

She told the mag: "I want to tell you everything, but I have to sew my lips together. It's hurt me in the past."

Looks like Jess is going to keep mum about John, 29, but the singer did confess: "Something big is happening. I am so happy right now."