Sophia Bush opened up about her 2005 annulment from ex-husband and former One Tree Hill costar Chad Michael Murray during an appearance on Bravo's Watch What Happens Live on Monday, Jan 6 Credit: Charles Sykes/Bravo/NBCU Photo Bank via Getty

Chad who? Sophia Bush may have moved on from the Chad Michael Murray chapter of her life, but fans of the actress clearly haven't. During an appearance on Bravo's Watch What Happens Live Monday night, the Chicago PD star answered a caller -- and then some -- on whether or not she keeps in touch with her ex. Click here for more pics of the actress.

"That's such an interesting question," the 31-year-old laughed. "But my mother once said to me that if you don't have anything nice to say, not to say anything at all."

Bush and Murray, 32, married in April 2005 after meeting on set of the TV series One Tree Hill in 2003. Five months later, the exes separated and filed for annulment after rumors surfaced that Murray allegedly cheated on the actress with Paris Hilton. Their divorce was finalized in December 2006.

As the brunette stunner toasted to the Michigan caller with a glass of wine, host Andy Cohen quickly followed up the question, asking if it was difficult to continue filming the teen drama after the pair's split.

The actress was impressively diplomatic in her reply. "At the end of the day we're grownups, and I actually think what's interesting about it is that when people split in a way that's unpleasant, they usually just go on quite literally hating each other—or the person in my situation hates the other person, whatever—but when you have to work with somebody for another half a decade, you kind of have to deal with it," Bush explained. "Because for me, at the end of the day, my job is my priority. And so I think at the end of it, it really let me just let go of it."

So, does she regret tying the knot with Murray all those years ago? "We were two stupid kids who had no business being in a relationship in the first place," Bush continued. "To all the other costars who've worked it out, more power to you."

After the breakup, Bush and fellow costar Austin Nichols had an on-and-off relationship for six years. Us Weekly exclusively confirmed their split in February 2012. She's currently dating Google program manager Dan Fredinburg. Murray announced his split from fiancee Kenzie Dalton -- an OTH cheerleader extra -- in September 2013 after seven years together. One month later, he stepped out with new Australian girlfriend and Left Behind costar, Nicky Whelan.