Question Summary:
I’m afraid my fiance will find out my previous relationship. What should I do?

Question Detail:

I am a convert to islam, al hum du lilah I was in a haram relationship before reverting to islam. Me and this woman were and still have love for each other. The relationship was broken off due to obvious reasons and I stayed on the straight path for quite some time. Unfortunately I engaged in haram activities (no intercourse) with another woman just one time. I felt guilty while committing this act and pleaded to stop multiple times, but continued. This only happened the one time and never again. I am now engaged to be married to my once girlfriend. I think about my mistake often and do not know how to forget this mistake. I seek forgiveness in Allah daily for this because I am constantly reminded for the mistake I made. I feel as if I cheated and she should know, but she will not accept me after this I am sure. Here is the punch line : she is in contact with this sister I committed awful acts with on a daily basis. I am scared they will talk or even accidentally talk about knowing me creating ripples that cannot be changed. Please help me in distress.

Answer :

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
May Allah keep you firm on Islam and strengthen your faith. Ameen.
It is a sign of your faith that you are remorseful and concerned about your past mistakes. Allah is the Most-Forgiving, the Most-Merciful. Never despair of His Mercy.  Combine this fear of Allah with hope in His Mercy by continuing to seek forgiveness daily (istighfar) and be confident that Allah's Mercy is greater than your sins.
Do good deeds as much as you can, paying special attention to all obligatory deeds: five times daily prayer (salah), fasting (sawm), etc.
My respected brother, you have made a commitment to Islam by reverting to the one, true faith. You have obtained the greatest treasure (Islam) and this is your key and ticket to Paradise. Now, your goal should be to avoid all sins and fulfill your obligations so that you can continue to make spiritual progress.
It is also a sign of your faith that you want to avoid unlawful relationships and are seeking a halal relationship. However, please understand that you cannot communicate with your fiance as you are still her a stranger to her. You should refrain from communicating with her  until you have married her (performed your nikah with her).
Secondly, you have mentioned that your fiance is in regular contact with the woman you had an unlawful relationship with in the past.
With regards to informing her, Allah has concealed your sin so you should not say anything to her. Revealing the affair will cause her a lot of pain and you have stated that you believe it will have an impact on your future marriage to her.
However, if you strongly believe that this woman will tell your fiance about your past, you can convey through another person to your fiance that you have in the past committed some sins and repented from them, without specifying any specific sin or specific person. Through a third party encourage her to also practice and adopt Islamic values.
We make dua that Allah enable you and your fiance to fulfill the sunnah of marriage and to have a happy, blessed future filled with obedience to Allah. Ameen
And Allah Ta’āla Knows Best
Sohail ibn Arif,
Student Darul Iftaa
Chicago, USA
Checked and Approved by,
Mufti Ebrahim Desai.