Divorce is not taboo. There are situations where divorce would be considered right and proper. I doubt any real Catholic would suggest that a woman whose husband had openly moved in with another woman, fathered children by her, and pledged to marry her, should not seek a divorce.
What sets the Catholic Church's position on divorce apart from some others is that divorced Catholics are not allowed to remarry. Since Michael and Jodi clearly do not care about doing what is right by the Catholic Church, I wouldn't think that should matter to them. And if Terri had ever recovered enough to want to remarry, she could have sought an annulment and could probably have gotten one under the circumstances, especially given that--unlike her husband--she is childless.