Dought & clear - , His wife committed zina twice with a Christian man; should he divorce her? If she apostatises will there be any sin on him?.

his wife after she committed adultery for the second time with a
christian man. He had forgive her the first timeand now after she had
travelled , she had committed adultery for the second time with
another christian man but the husband this time want to divorce
herbecause he is an Islamic teacher and he fears for his reputation.
But he fears if he divorce this woman she will leave Islam and go back
to Christianity and also she does not want to wear hijab but pray and
fast . they have grown up children. Please advise The husband does not
want to be responsible for the wife leaving Islam.
Praise be to Allaah.
Firstly:
If a woman persists an immoral action and doesnot repent from it or
give it up, even if the matter did not go as far as zina, such as if
she had a relationship with this Christian man or anyone else, then it
is not permissible for the husband to keep her, because that is a kind
of cuckoldry (diyaathah), and cuckoldry is a major sin, because of the
report narrated by al-Nasaa'i (2562) from 'Abd-Allah ibn 'Umar (may
Allah be pleased with him) who said: The Messenger of Allah (blessings
and peace of Allah be upon him) said: "There are three at whom Allah,
may He be glorified and exalted, will not look on the Day of
Resurrection: the one who is defiant towards his parents, the woman
who imitates men, and the cuckold."
Classed as saheeh by al-Albaani in Saheeh al-Nasaa'i.
The cuckold is the one who approves of evil conduct in his family.
Shaykh al-Islam Ibn Taymiyah (may Allah be pleased with him) was asked
about the one who came into his houseand found a stranger with his
wife, so he gaveher her dues and divorced her by talaaq, then he went
back and reconciled with her and heard that she had been found with a
non-mahram man.
He replied: In the hadeeth from the Prophet (blessings and peace of
Allah be upon him) it says that when Allah, may He be glorified and
exalted, created Paradise, He said: "By My glory and majesty, no
miser, liar orcuckold will enter you." The cuckold is the one who has
no protective jealousy or pride. In al-Saheeh it is narrated that the
Prophet (blessings and peace of Allah be upon him) said: "The believer
has protective jealousy (gheerah) and Allah has protective jealousy,
and the protective jealousy of Allah is that no slave should do that
which is forbidden to him." And Allah says (interpretationof the
meaning): "The adulterer — fornicator marries not but an adulteress —
fornicatress or a Mushrikah; and the adulteress –fornicatress, none
marries her except an adulterer — fornicater or a Mushrik [and that
means that theman who agrees to marry (have a sexual relation with) a
Mushrikah (female polytheist, pagan or idolatress) or a prostitute,
then surely, he is either an adulterer — fornicator, or a Mushrik
(polytheist, pagan or idolater). And the woman who agrees to marry
(have a sexual relation with) a Mushrik (polytheist, pagan or
idolater) or an adulterer — fornicator, then she iseither a prostitute
or a Mushrikah (female polytheist, pagan, or idolatress)]. Such a
thingis forbidden to the believers (of Islâmic Monotheism)" [al-Noor
24:3]. The correct scholarly opinion is that it is not permissible to
marry a zaaniyah (a woman who commits fornication or adultery) until
after she has repented. The same applies if the wife commits zina: the
husband has no right to keep her in that case; rather he should leave
her, otherwise he will bea cuckold (duyooth). Endquote from Majmoo'
al-Fataawa, 32/141
Secondly:
If the woman has repented, turned over a new leaf and is living a
righteous life, and she has cut off all ties to thatnon-mahram man,
then the husband may keep her, and perhaps Allah will reward him for
treating her kindly and concealing her sin.
We have stated that it is not permissible for him to keep her as his
wife ifshe committed zina and has not repented from it sincerely, and
we stated that if she repents and turns over a new leaf, then he may
keep her and conceal her sin, if hehas the patience to do that. What
we have said about it being permissible to keep her if she repents is
not obligatory for him, rather it is up to him. In all cases he may
leave her, because zina on the part of the wife is extremely abhorrent
andmost people cannot forgive that. And if he divorces her, then he is
not responsible for whatshe commits of sin, and if she apostatises
from Islam, she alone is responsible for that, because she is
accountable and of sound mind: if she does good deeds that it is in
her favour and if she does bad deeds then it counts against her.
We ask Allah to protect the Muslims from all trials, evils and turmoil.