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.
Dear questioner, we would like to thank you for the great confidence you place in us, and we implore Allah Almighty to help us serve His cause and render our work for His Sake.
Answering your question, Sheikh Ahmad Kutty, a Senior Lecturer and an Islamic Scholar at the Islamic Institute of Toronto, Ontario, Canada, states:
The expiation for sexual intercourse while fasting is to fast two months consecutively; if one cannot do so, then feeding sixty poor persons.
This expiation concerns sexual intercourse with one’s lawful spouses.
Yours is an even more grievous a sin. So, firstly, you need to seek sincere repentance and beg for the mercy of Allah and expiate it by fasting two months for each day you have broken; in case you cannot, do so by feeding sixty poor persons. On top of these, you should follow it up with as many good deeds as you can. Allah says, “Good deeds wipe out the bad.” (Hud 11:114) The Prophet (peace be upon him) said, “Allah does not wash out evil act through evil; rather He washes it out through good deeds.”
Allah Almighty knows best.