CC Madhya 15.264

ṣāṭhīre kaha — tāre chāḍuka, se ha-ila ‘patita’
‘patita’ ha-ile bhartā tyajite ucita
Word for word: 
ṣāṭhīre kaha — inform Ṣāṭhī; tāre chāḍuka — let her give him up; se ha-ila — he has become; patita — fallen; patita ha-ile — when one has fallen; bhartā — such a husband; tyajite — to give up; ucita — is the duty.
Translation: 
“Inform my daughter Ṣāṭhī to abandon her relationship with her husband because he has fallen down. When the husband falls down, it is the wife’s duty to relinquish the relationship.
Purport: 

Śrīla Sārvabhauma Bhaṭṭācārya considered that if Amogha were killed, the killer would suffer sinful reactions for killing the body of a brāhmaṇa. For the same reason, it would have been undesirable for the Bhaṭṭācārya to commit suicide because he also was a brāhmaṇa. Since neither course could be accepted, the Bhaṭṭācārya decided to give up his relationship with Amogha and never see his face.

As far as killing the body of a brāhmaṇa is concerned, Śrīmad-Bhāgavatam (1.7.53) gives the following injunction concerning a brahma-bandhu, a person born of a brāhmaṇa father but devoid of brahminical qualities:

śrī-bhagavān uvāca
brahma-bandhur na hantavya
ātatāyī vadhār-haṇaḥ

“The Personality of Godhead Śrī Kṛṣṇa said, ‘A brahma-bandhu is not to be killed, but if he is an aggressor, he must be killed.’ ”

Quoting from the smṛti, Śrīla Śrīdhara Svāmī comments on this quotation from Śrīmad-Bhāgavatam:

ātatāyinam āyāntamapi vedānta-pāragam
jighāṁ santaṁ jighāṁsīyān
na tena brahma-hā bhavet

“ ‘An aggressor intent on killing may be a very learned scholar of Vedānta, yet he should be killed because of his envy in killing others. In such a case, it is not sinful to kill a brāhmaṇa.’ ”

It is also stated in Śrīmad-Bhāgavatam (1.7.57):

vapanaṁ draviṇādānaṁsthānān niryāpaṇaṁ tathā
eṣa hi brahma-bandhūnāṁ
vadho nānyo ’sti daihikaḥ

“Cutting the hair from his head, depriving him of his wealth and driving him from his residence are the prescribed punishments for a brahma-bandhu. There is no injunction for killing the body.”

As far as Ṣāṭhī, the daughter of Sārvabhauma Bhaṭṭācārya, was concerned, she was advised to give up her relationship with her husband. Concerning this, Śrīmad-Bhāgavatam (5.5.18) states, na patiś ca sa syān na mocayed yaḥ samupeta-mṛtyum: “One cannot be a husband if he cannot liberate his dependents from inevitable death.” If a person is not in Kṛṣṇa consciousness and is bereft of spiritual power, he cannot protect his wife from the path of repeated birth and death. Consequently such a person cannot be accepted as a husband. A wife should dedicate her life and everything to Kṛṣṇa for further advancement in Kṛṣṇa consciousness. If her husband abandons Kṛṣṇa consciousness and she gives up her connection with him, she follows in the footsteps of the dvija-patnīs, the wives of the brāhmaṇas who were engaged in performing sacrifices. The wife is not to be condemned for cutting off such a relationship. In this regard, Śrī Kṛṣṇa assures the dvija-patnīs in Śrīmad-Bhāgavatam (10.23.31-32):

patayo nābhyasūyeranpitṛ-bhrātṛ-sutādayaḥ
lokāś ca vo mayopetā
devā apy anumanvate

na prītaye ’nurāgāyahy aṅga-saṅgo nṛṇām iha
tan mano mayi yuñjānā
acirān mām avāpsyatha

“My dear dvija-patnīs, rest assured that your husbands will not neglect you on your return, nor will your brothers, sons or fathers refuse to accept you. Because you are My pure devotees, not only your relatives but also people in general, as well as the demigods, will be satisfied with you. Transcendental love for Me does not depend upon bodily connection, but anyone whose mind is always absorbed in Me will surely, very soon, come to Me for My eternal association.”