Sometimes “insult” (not really insult …but they may feel that way …though they ought to think how they are shaming her etc as another noted) will happen in life and cannot be avoided.
It is black and white.

Do good, avoid evil.
She is coming here for advice. So saying “But it’s the OP’s situation to handle and she can certainly handle in the way you wish.” is not fitted to the occasion here.
One may not approve or praise etc the evil of others.
It is in no way “scrupulously enforcing mortality” -by definition.
It may be that a Spouse may not be able to prevent wrongful things from happening in their home -but they ought to seek -lovingly and calmly and with truth to prevent such and they are not to cooperate in any wrongful way (see CCC above) in the objective sin of others.
Yes it must be handled delicately as possible -with love, truth, and gentleness. And it may not be possible for her to change their minds or what will happen - but the choices
she makes and the actions she does - must be Christian. In truth and love and gentleness.