Wa `alaykum as-Salamu wa Rahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Dear brother, thank you for your question that shows your sincere repentance.
Surely you have made a big mistake, but it is good of you that you have asked Allah Almighty for forgiveness.
Moreover, you should also ask Allah Almighty to protect you from any evil that guy might think of.
Responding to your question, Dr. Muhammad Salama, PhD in Islamic Studies in English and an Assistant Professor at the Faculty of Islamic Science, Al-Madinah International University, states:
It was a big mistake, sister, to try to please a person by displeasing Allah. You see the result now. This is also the result of mingling with men and thinking that a fiancé has a right to mingle freely with his fiancé.
First, you have to repent sincerely to Allah and earnestly ask Him to forgive your sin.
Now, perhaps your fiancé has repented sincerely and has changed his opinion toward you after what you did. In this case, just pray to Allah to compensate you and grant you a better one. Perhaps, also, he gives himself time to re-estimate your relationship.
But if he has not repented sincerely, then no one can expect what he will do. All you can do is to pray hard to Allah to preserve your reputation and to protect you against any evil intended by this person.
Also ask Allah to grant you a good, religious husband to help you abide by the teachings of your religion.
Allah is All-Knowing, All-Powerful and the Accepter of Repentance; in whose Hands are the treasures of everything. So, just try to please Him and you will see the result.