Praise be to Allah.
Zina (fornication or adultery) is a major sin. Allaah has forbidden doing the things that lead to it and has prescribed the hadd punishment for the one who does it, and He has warned adulterers of punishment in the Hereafter.
Allaah says (interpretation of the meaning):
“And come not near to unlawful sex. Verily, it is a Faahishah (i.e. anything that transgresses its limits: a great sin), and an evil way that leads one to hell unless Allaah forgives him”
Ibn Jareer al-Tabari (may Allaah have mercy on him) said:
“And come not near” O people
“to unlawful sex. Verily, it is a Faahishah (i.e. anything that transgresses its limits: a great sin)”. Zina (translated here as “unlawful sex”) is a great sin.
“and an evil way” i.e., the way of zina is an evil way, because it is the way of the people who disobey Allaah and go against His command; what a bad way is the way that leads a person to the fire of Hell.
Tafseer al-Tabari (17/438).
Shaykh ‘Abd al-Rahmaan al-Sa’di (may Allaah have mercy on him) said:
The prohibition on approaching it is more eloquent than a simple prohibition on doing it, because that includes the prohibition on all the things that lead to it and promote it, because “the one who grazes his flock around a protected areas will soon transgress upon it,” especially in a matter of this nature when the motive is very strong. Allaah describes zina as abhorrent, as He says “it is a Faahishah (i.e. anything that transgresses its limits: a great sin)”, i.e., it is a sin which is abhorrent according to sharee’ah, reason and common sense, because it is a transgression against Allaah, and against the woman and her family or husband, and it leads to immorality, confusion of lineages and other evil consequences.
“and an evil way” means: what an evil way is the way of the one who dares to commit this grave sin.
Tafseer al-Sa’di (p. 457).
See also the answers to questions no. 76060, 20983 and 95754.
With regard to the abortion, if the soul had been breathed into the foetus, then this is another crime in addition to the crime of zina. If the soul had not yet been breathed into the foetus then it is less serious.
For a detailed discussion on that, please see the answers to questions no. 11195, 13319, 13331 and 90054.
We praise Allaah for having enabled you to repent, and we hope that it is sincere repentance. The conditions of sincere repentance include: regretting the sins that you have committed, and immediately giving up that immoral action, and everything that leads to it such as contact, correspondence and dates. The conditions of repentance also include resolving not to return to this deed.
You also have to do a lot of righteous deeds, such as prayer, reading Qur’aan and fasting, so as to strengthen your faith and piety. Good deeds erase bad deeds and sincere repentance erases that which came before it, and turns bad deeds into good deeds. Allaah says – after mentioning the sins of shirk (associating others with Allaah), murder and zina – (interpretation of the meaning):
“Except those who repent and believe (in Islamic Monotheism), and do righteous deeds; for those, Allaah will change their sins into good deeds, and Allaah is Oft‑Forgiving, Most Merciful”
With regard to marrying that criminal, you should understand that in order for the marriage of a man and woman who had committed zina to be valid, it is essential that they repent sincerely. It seems to us from your questions that he has not repented from what he did, rather he had added to the first calamity the other bad things that he is doing, such as smoking hasheesh and drinking intoxicants. What we think is that one who is like this also does not pray. If this is indeed the case, then it is definitely not permissible to accept him as a husband, because not praying is kufr that puts a person beyond the pale of Islam, and it is not permissible for a Muslim woman to marry a kaafir.
For a more detailed discussion on the issue of marrying a zaani (one who commits fornication or adultery), please see the answers to questions no. 85335, 87894 and 96460.
With regard to having an operation to repair the hymen, this is haraam, because it is deceiving the one who marries you.
For a detailed discussion of this matter, please see the answer to question no. 844.
With regard to telling your future husband that you lost your virginity in this haraam relationship, that is not permissible, because it is exposing your faults, and the Muslim is required to conceal his faults. You can use double entendres in your speech. It is well known that the hymen may be broken by means of something other than intercourse in some cases, so you can make the most of that by using a double entendre.
See the answer to question no. 42992.
But if it is possible to encourage this person to repent sincerely and pray regularly, and he shows sincerity and signs of repenting and praying regularly, then there is nothing wrong with accepting him as a husband. Undoubtedly this solution would be easier for you, and more concealing for you, but how could one believe a person like that?!
We ask Allaah to accept your repentance and set your affairs straight, and to conceal our faults and yours in this world and in the Hereafter.
And Allaah knows best.