The Sex and the City creator announced that she would end the nine-year marriage last week but has since apparently discovered Askegard's affair with fellow ballerina Georgina Pazcoguin, reports The New York Post.
"The divorce was proceeding amicably, then Candace found out about Georgina and became very upset," a source told the paper.
"She believes their affair could have gone on for some time. Humiliated, it was her idea to take the unusual step of naming Georgina as a co-respondent in the divorce papers."
Bushnell declined to comment on the affair, with Askegard saying only: "I respectfully decline to comment further regarding this matter. Georgina has no comment at this time either."
Upon the original announcement that she would divorce Askegard, Bushnell said: "I respect his desire to pursue his own happiness and hope that we will continue to be friends."
Earlier this year, Bushnell suffered a cracked pelvis after injuring herself while horseback riding.
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