Come on man, are you serious? Do you honestly think that the eye-for-an-eye approach will help their marriage heal and bring her husband to the Lord? You have to know that if she does this, that her husband would only become angry with her and there would be more finger-pointing and more accusing, and the gap in their marriage would widen even further. I just don't believe this God's best for marriage.
The scriptures below describe how we are to treat our brethren (men and women), Peter 3:9 speaking to the marriage relationship directly...
1Pe 3:9-12 LITV not giving back evil for evil, or reviling against reviling; but, on the contrary, give blessing; knowing that you were called to this in order that you might inherit blessing. (10) "For the one desiring to love life, and to see good days, let him restrain his tongue from evil, even his lips not to speak guile. (11) Let him turn aside from evil, and let him do good. Let him seek peace, and pursue it; (12) because the eyes of the Lord are on the righteous, and His ears open to their prayer. But the face of the Lord is against any doing evil things."
Rom 12:9-21 LITV Let love be without dissimulation, in horror fleeing from evil, cleaving to the good, (10) in brotherly love to one another, loving fervently, having gone before one another in honor; (11) in diligence, not slothful, fervent in spirit, serving the Lord; (12) in hope, rejoicing; in affliction, enduring; in prayer, steadfastly continuing; (13) imparting to the needs of the saints, pursuing hospitality. (14) Bless those persecuting you; bless, and do not curse. (15) Rejoice with rejoicing ones, and weep with weeping ones; (16) minding the same thing toward one another, not minding high things, but yielding to the lowly. Do not become wise within yourselves; (17) returning evil for evil to no one; providing right things before all men. (18) If possible, from you being in peace with all men; (19) not avenging yourselves, beloved, but giving place to wrath, for it has been written, "Vengeance is Mine," "I will repay," says the Lord. (20) Then "if one hostile to you hungers, feed him; if he thirsts, give him drink; for doing this you will heap coals of fire on his head." (21) Do not be overcome by evil, but overcome the evil with good.
1Th 5:14-15 LITV And we exhort you, brothers, to warn the disobedient ones, comfort those that are fainthearted, cleave to the ones being weak, be long-suffering towards all. (15) See that not any one returns evil for evil to anyone, but always pursue the good, both towards one another and towards all.
I think it would be better to approach the situation in love and compassion, no matter how bad it may look. God can change these situations for our good and His glory if we trust in Him and ask Him for help.
- blitzn