The Coronation Street actress, who was seen yesterday without her wedding ring for the first time, is said to be feeling ready to move on following the couple's split in July.
"Kym has turned a corner," a source close to the couple told the Mirror. "Jamie's behaviour has been bothering her for some time now. She feels she has no choice."
"But she doesn't want a messy divorce," added the friend. "It must be as quick and as amicable as possible."
Despite rumours that Kym had a five-month fling with her Coronation Street co-star Oliver Mellor, it is Jamie's behaviour that has meant she feel she can no longer stay in the marriage.
Kym, who plays Michelle Connor in Corrie, is said to have tried to stay with her husband of one year for the sake of her children.
The 37-year-old has two-year-old daughter Polly with Jamie, 33, as well as children, David, 18 and Emily, 15, from her relationship with builder Dave Cunliffe.
The former Hear'Say singer was also married to EastEnders actor Jack Ryder in 2002 although the pair called time on their marriage in 2009 when it emerged that Kym had had an affair with Jamie.