The people heaping opprobrium on Amy Grant for the divorce fail to appreciate the difficulty of living with people who have a substance abuse problem. There may have been times that Amy feared for her physical safety, watched her hard-earned money disappear, and grew tired of the constant lies that addicts tell.
A TV preacher once told a woman that she had a right to divorce an addicted husband and remarry. His reasoning: the Pauline privilege allows divorce and remarriage because of abandonment. An addict has abandoned his marriage for a drug. The abandonment is real, even if the husband is still living in the home.
It is also my guess that a cocaine addict will probably have committed adultery somewhere along the way because they are hyped up and have impaired judgment. This may not be the case with other drugs.
On the other hand, lots of people with drug problems are self-medicating depression, bipolar disorder or, perhaps, the dysfunction that comes from head injuries. Many of histories of being abused. Therefore, it might be good to refrain from trashing the ex-husband, too.