So what will happen to her?
This question is out of the knowledge humans may answer and is a kind of question like:
Which are the (kinds of) things that only Allah knows about and no human can safely give answer about it?
None can safely say what Allah will do or not because none of us has knowledge beyond what Allah has told us via his prophets() and revelations. And we can't question what He does:
He is not questioned about what He does, but they will be questioned. (21:23)
We may pray for her forgiveness, but the decision is not ours, and hope for Allah's Mercy.
As good Muslim we should know that we won't enter jannah by our deeds, but because of Allah's Mercy!
As for whether it can be forgiven this is addressed in Can suicide be forgiven?
What we should know about suicide
Suicide is a crime and a major sin (#29 in the book the major sins -Kitab al-Kaba'ir الكبائر- of imam a-Dhahabi):
Allah says in the qur'an:
O you who have believed, do not consume one another's wealth unjustly but only [in lawful] business by mutual consent. And do not kill yourselves [or one another]. Indeed, Allah is to you ever Merciful. (4:29)
And you may find in the sunnah many ahadith on the topic:
The Prophet (ﷺ) said, "He who commits suicide by throttling shall keep on throttling himself in the Hell Fire (forever) and he who commits suicide by stabbing himself shall keep on stabbing himself in the Hell-Fire."
The Prophet (p.b.u.h) said, "Whoever intentionally swears falsely by a religion other than Islam, then he is what he has said, (e.g. if he says, 'If such thing is not true then I am a Jew,' he is really a Jew). And whoever commits suicide with piece of iron will be punished with the same piece of iron in the Hell Fire." Narrated Jundab the Prophet (ﷺ) said, "A man was inflicted with wounds and he committed suicide, and so Allah said: My slave has caused death on himself hurriedly, so I forbid Paradise for him."
We witnessed (the battle of) Khaibar. Allah's Messenger (ﷺ) said about one of those who were with him and who claimed to be a Muslim. "This (man) is from the dwellers of the Hell-Fire." When the battle started, that fellow fought so violently and bravely that he received plenty of wounds. Some of the people were about to doubt (the Prophet's statement), but the man, feeling the pain of his wounds, put his hand into his quiver and took out of it, some arrows with which he slaughtered himself (i.e. committed suicide). Then some men amongst the Muslims came hurriedly and said, "O Allah's Apostle! Allah has made your statement true so-and-so has committed suicide. "The Prophet (ﷺ) said, "O so-and-so! Get up and make an announcement that none but a believer will enter Paradise and that Allah may support the religion with an unchaste (evil) wicked man.
The Prophet (ﷺ) said, "Whoever swears by a religion other than Islam (i.e. if he swears by saying that he is a non-Muslim in case he is telling a lie), then he is as he says if his oath is false and whoever commits suicide with something, will be punished with the same thing in the (Hell) fire, and cursing a believer is like murdering him, and whoever accuses a believer of disbelief, then it is as if he had killed him."
Therefore suicide is a major sin and a stupid one too because the person committing it is forbidding for him-/herself the option of repentance, which is given for almost all sins no matter how big they are.
Imam Ahmad narrated a rather strange hadith which goes against the majority view of the scholars stating that the Prophet () perform the janazah prayer on suicidal person.
Rights of the husband on the wife
First of all the thinking that a wife must follow her husband's orders is very restricted and not a blue print as many people wrongly think. As explained in Wife refuses to visit husbands parents house
There are three cases where a wife must not follow her husbands orders:
- If she'd be committing a sin as is the case with suicide. Allah says:
O you who have believed, obey Allah and obey the Messenger and those in authority among you. And if you disagree over anything, refer it to Allah and the Messenger, if you should believe in Allah and the Last Day. That is the best [way] and best in result. (4:59)
Sheikh a-Shinqiti in his tafssir pointed at the repetition of Allah and the prophet () which emphasizes that their orders must be followed, while the authority, be it a leader, a father or a husband was not repeated so their orders are not set equal to those of Allah and His Messenger. Further a known fiqh rule derives from the hadith saying:
`There is no obedience to any created being if it involves disobedience to Allah, may He be glorified and exalted.” (Musnad imam Ahmad)
- In case one would harm himself and suicide is such a case. Allah says:
And spend in the way of Allah and do not throw [yourselves] with your [own] hands into destruction [by refraining]. And do good; indeed, Allah loves the doers of good. (2:195)
- The third case is covered in the linked post: A wife must only follow her husbands orders on matters related to her marriage (for example if he asks her some of his marital rights like intercourse).
Causing death to a person and other implications of the case
Scholars say that people who cause or urge a person to death or suicide are committing one of the worst sins, but they could repent and be forgiven. I couldn't find any scholar saying that they take part of the sin of suicide.
However there's a hadith qualified as weak in Sunan ibn Majah saying -I've corrected a typo from the sunnah.com translation-:
“Whoever helps to kill a believer, even with half a word, he will meet Allah (SWT) with (the words) written between his eyes, 'He has no hope of the mercy of Allah (SWT).”
This hadith literally means: If a person asked you shall I kill "X" and you say: "Ye" and stopped it would be to late for you. But this doesn't seem to go along with the verse:
Indeed, Allah does not forgive association with Him, but He forgives what is less than that for whom He wills. And he who associates others with Allah has certainly fabricated a tremendous sin. (4:48)
Which applies to a murder, a suicidal person and any sinner.
Further as we know a persons intention play a high role in Islam and at least Allah knows best!