Is it a Good Idea to Contact an Ex After a Break-up?

Earlier this year we heard about one of the biggest break-ups in Hollywood. The divorce of Tom Cruise and Katie Holmes. After 5 yrs. of marriage Katie decided to end the marriage. Both seem to  have moved on with their lives and now  rumors are surfacing that Katie has reached out to one of her exes....

She allegedly contacted her Dawson's Creek co-star and ex-boyfriend Joshua Jackson. Sources say she hadn't talked to him in years and just wanted to see how he's doing and "catch up." I wonder however, if she has something else in mind? Now that she's a single lady, maybe she's hoping to rekindle an old flame, see if there any feelings still there. Do you think this is a good idea? Aren't you supposed to leave the past behind? If it didn't work out the first time what makes you think it will now? What do you think?