"My job is my job," the One Tree Hill star says of acting with estranged hubby Chad Michael Murray

One Tree Hill star Sophia Bush says she has no problem shooting intimate scenes with her costar Chad Michael Murray, despite the fact they are in the middle of a divorce.

“My job is my job, and my personal life is my personal life, and I keep them separate,” the brunette beauty told PEOPLE. “It’s my job. It’s not always easy, but it’s my work – it’s what I love and take pride in, and I won’t let that slack because of personal circumstances.”

Bush, 23, made the comments Tuesday night at the “It Bags Against Breast Cancer” charity auction at Henri Bendel in New York. She was composed and forthright about the couple’s split in September after five months of marriage – though she hinted that Murray’s behavior was behind the breakup.

“I’m a big girl. I’m a strong girl,” she told PEOPLE. “It’s not that I don’t respect other women in my position, but there are things I won’t forgive. I have too much going on in my life to focus on.”

Bush plays the character Brooke on One Tree Hill, while Murray, 24, plays her love interest Lucas. The WB show’s script has required the ex-couple to cozy up to each other. An insider recently told PEOPLE: “Their story lines will be crossing as Brooke tries to get Lucas to come back to her. That will be the real test of their acting abilities.”

At the time, the source said the two were “being professional and trying not to let this break between them affect their work or careers. They know that whatever’s happened to them in real life has to stay home.”

The couple met in 2003 while filming One Tree Hill and were engaged in 2004. They married in April at Santa Monica’s Hotel Casa Del Mar.