Assalaamualaikum. I have been severly suffering, and I ask God to make you a reason to help me out. I used to be in a haram relation with this girl when I was a teenager (it included so much sins) until God guided me to the right path and I started quitting alot of sins and repenting until it was time to end this relation (this girl is from a religious family just like myself, and we used to do the sins together), until God granted me the power to leave this relation, and I promised her that if she repents to God, like I am doing, we will end up together with a halal marriage. After four years, my faith went dramatically down compared to where I was, and I ended up talking to her again, knowing that she slightly changed to the better. I then decided to propose to her and was very happy. I asked her (which was wrong) whether she got into any physical relations with anyone since we broke up, and she denied that, but it was eating me inside that she (perhaps) did do so. Anyway, after getting engaged, I cornered her to tell me whether she had done so, and she confessed, and since then, I am going through a horrible breakdown. I do not know whether you believe in this, but we are truly both obsessed with each other, and the path which she took after we broke up was because of not believing in God properly. Anyway, I feel that she is not pure (although she had a past before me, which I totally accepted, but this last guy I cannot). Nonetheless, I told her that if she gets really close to God by quitting the major sins that she does, we will get married. And if not, we will not be together. Do you think this would make me forget and push me back closer to God, or should I immediately end this relation and look for a pure girl and start my life over? (I am scared that my love for this girl will haunt me with all the pain that she has caused me.) May Allah reward you, Shaykh.
All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.
Praise be to Allah, Who guided you and brought you back to Him before you die. We ask Allah to help you, guide you, and enable you to do that which He likes and is pleased with.
Your question included committing many sins, including the forbidden relationship and asking your fiancée about her forbidden relationship.
We advise you to repent to Allah from all sins and become steadfast on His religion. If you love that girl, then the best solution is to marry her. So we advise you to marry her if she has repented to Allah with a sincere repentance and has become steadfast on His religion. Do not think about her previous sins; what is important is her situation now.
So if it appears that she has become righteous and the signs of repentance appear on her, then we advise you to marry her and not abandon her to marry someone else.
But if she did not sincerely repent, then you should forget her and look for another religious woman to marry, as there are many women out there, and you do not know who is better for you.
We ask Allah to enable you to do that which is best.