Chandler tells Monica that he will divorce her if she does not disown Ross, which would humiliate her; later, Ross tells Monica (untruthfully) that Chandler is having an affair with Phoebe, which Monica believes.
He will divorce her. This is what Chandler tells Monica. She does not disown Ross. Ross would humiliate her. Chandler is having an affair with Phoebe. This is what Ross tells Monica (untruthfully). Monica believes.