I think, Melchior, that what is boils down to is that ANNULMENT, not divorce, can be sought in this woman’s case. The argument would be that, at the time the marriage took place, the husband would not have been able to give valid consent to the marriage. While not an ex propter hox, it seems probable, though not certain, that the husband at the time of the marriage did NOT intend for this to BE a sacramental marriage, and the later RESULT was that he chose to engage in adultery and to seek a divorce.
(Right now my annulment is before the tribunal–my husband likewise engaged in adultery as well as some other matters too heinous and private to discuss on an open message board–and the petition for cause does rest on whether or not one or both parties was ABLE to give valid consent to the marriage at the time the marriage took place.)
So I hoping that both I–and your friend–will be able to get annulments. This will have NO effect on either her or my children, BTW. And I’m not planning marriage, or even dating, as I still consider myself married, despite the divorce and annulment petition, until and unless the Church herself says otherwise.
And don’t forget to tell your friend that she MAY receive communion despite the divorce! I was miserable for nearly a year thinking that I could NOT receive, until I moved and the priest at my current parish informed me otherwise. It isn’t the DIVORCE that would bar an INNOCENT person like the victim of an adulterer, but being the adulterer or engaging in mortal sin. Innocent victims of divorce aren’t in sin.
Best wishes to you, and I’m glad your friend has a caring friend like you.