Praise be to Allah.
We praise Allah, may He be glorified and exalted, for saving you both from that terrible experience and protecting your honour and your lives. You have to give thanks to Allah your Lord and adhere to obedience to Him, for Allah has honoured you with a great blessing.
Suicide -- which means killing oneself -- is a major sin and it is not permissible for anyone to do it, no matter how difficult the circumstances of the one who wants to commit suicide get and no matter how bad his situation is. The hadeeth is general in application, and it is not permissible to make exceptions to it without a text from the infallible Revelation.
It was narrated that Abu Hurayrah said: The Messenger of Allaah (S) said: “Whoever throws himself down from a mountain and kills himself will be throwing himself down in the Fire of Hell for ever and ever. Whoever drinks poison and kills himself will be sipping it in the in the Fire of Hell for ever and ever. Whoever kills himself with a piece of iron will have that iron in his hand, thrusting it into his belly in the Fire of Hell for ever and ever.”
Narrated by al-Bukhaari (5442) and Muslim (109).
The woman who is threatened with rape must defend herself from that sinful action, even if it leads to killing that evildoer and criminal.
It must also be understood that if Allah, may He be exalted, decreed that she should fall victim to rape, she is not a zaaniyah (fornicator or adulterer) and the hadd punishment for zina should not be carried out on her. There is no difference of opinion concerning this among the scholars as far as we know.
Ibn ‘Abd al-Barr (may Allah have mercy on him) said:
There is no difference of opinion as far as I know among the scholars of the earlier and later generations concerning the fact that the woman who is forced into zina is not to be subjected to the hadd punishment, if it is true that she was forced and raped.
The Messenger of Allah (blessings and peace of Allah be upon him) said: “Allah has pardoned for my ummah mistakes, forgetfulness and what they are forced to do.”
See also the answer to question number 4017.
With regard to a woman killing herself because of rape, there are two scenarios:
where she kills herself before she is raped because she thinks it is most likely that this will happen to her;
where she kills herself after being raped, for fear of shame that will befall her or her husband or her family, or all of them.
In both cases it is not permissible for the woman to kill herself, and that is not a legitimate excuse for killing oneself. Rather she has to defend herself with whatever strength she has in the first case and then accept with patience whatever Allah decrees and seek reward for her calamity with her Lord. In the second case, she is not a sinner and is not to be blamed for what has happened to her; rather she has been wronged. But if she kills herself, she will be wronging herself and committing a grave sin.
It says in Fataawa Dar al-Ifta’ al-Masriyyah (2/277):
It is not permissible for her to kill herself in order to escape being forced into zina, because killing herself is an abhorrent crime and Allah does not accept the one who does it and is not pleased with him. In that case she would be no less sinful than one who kills a soul that Allah has forbidden anyone to kill unlawfully. Allah, may He be exalted, says (interpretation of the meaning):
“And do not kill yourselves (nor kill one another). Surely, Allaah is Most Merciful to you”
And the Prophet (blessings and peace of Allah be upon him) said, as was narrated from Abu Hurayrah (may Allah be pleased with him): “Whoever kills himself with a piece of iron will have that iron in his hand, thrusting it into his belly in the Fire of Hell for ever and ever. Whoever drinks poison and kills himself will have his poison in his hand, sipping it in the Fire of Hell for ever and ever. Whoever throws himself down from a mountain and kills himself will be throwing himself down in the Fire of Hell for ever and ever.” And it was narrated from Jaabir (may Allah be pleased with him) that a man killed himself with a broad arrow head and the Prophet (blessings and peace of Allah be upon him) did not offer the funeral prayer for him. Narrated by the group except al-Bukhaari.
This is what was stated by Shaykh al-Albaani (may Allah have mercy on him) in his fatwa. He was asked:
If a Muslim woman is attacked and the aggressors want to commit immoral actions with her, can she kill herself if she is afraid of that?
That is not permissible.
Silsilat al-Huda wa’l-Noor, tape no. 451
And Allah knows best.