The Coronation Street actress admitted adultery and agreed to pay part of the legal bill during the brief legal hearing, says the Daily Mail.
Marsh, 32, did not contest the decree nisi and stated "yes" when asked if she had been involved in an affair. Former EastEnders actor Ryder, 27, said in the court papers that he had first discovered the adultery last July after the couple had separated, when Marsh, who plays Michelle Connor in the ITV soap, and Hollyoaks star Jamie Lomas went public with their relationship.
The couple, who lost their baby, named Archie, earlier this year when he was born 18 weeks premature, went on to announced their engagement in December.
Ryder and Marsh, who married in August 2002, vowed to remain friends when they parted ways in March last year.