Fatwa ID: 04102
Answered by: Maulana Maruf Ahmed
Assalamwalikum. I have a question regarding conditional divorce. I am still unmarried and I haven't had any nikah but I placed a condition on the girl if you had a sexual relationship with someone you will be divorced? Is this divorce valid before nikah? Can I revoke my decision?
بِسْمِ اللهِ الرَّحْمنِ الرَّحِيْم
In the name of Allah, the Most Gracious, the Most Merciful
Issuing a divorce that is subject to the fulfillment of a condition is known as Ta’liq al-Talaq (conditional divorce).
Divorce can only be issued once nikah has taken place. This includes Ta’liq al-Talaq. 
The only case of Ta’liq al-Talaq which is made before marriage and is effective is if someone makes the condition of marriage itself (i.e. he says “if I marry you, then you are divorced”). 
Therefore, in the scenario mentioned in the question, divorce will not take place, unless you repeat those words after marriage, in which case divorce will take place if she did have any previous sexual relations.
Only Allah knows best
Written by Maulana Maruf Ahmed
Checked and Approved by Mufti Mohammed Tosir Miah
Darul Ifta Birmingham
 Al-Aini, Umdatul Qari: vol. 20 pg. 245. Dar Ihya al-Turath al-Arabi, Beirut.
 Ibn Abideen, Radd al-Muhtar: vol. 3 pg. 744. Dar al-Fikr, Beirut.
 Ibn Abideen, Radd al-Muhtar: vol. 3 pg. 345. Dar al-Fikr, Beirut.