Answer
Wa `alaykum As-Salamu waRahmatullahi 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.
In this fatwa:
Your marriage is valid as long as you have repented of your sin.
In his response to your question, Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states:
Your marriage is valid as long as you have repented of your sin. The fact you were pregnant does not make a difference as long as you married the same person who made you pregnant.
Having said I should remind you that fornication and adultery are both most heinous sins in Islam. So, it behooves everyone who is guilty of such offenses to seek repentance. Repentance, however, is not merely uttering some words to that effect; rather it entails taking steps to change and make amends.
Allah Almighty knows best.