The guilt is overwhelming you. You feel there is no way back from this sin. You’ve even lost hope that Allah will ever forgive you.
Did you know that this feeling is a sign of iman. The Prophet (pbuh) said, “If your good deeds make you happy and your bad deeds make you sad, then you are a believer.”
Furthermore, we have a dua from our Lord in the Quran which we can recite to earn His forgiveness.
They said, “Our Lord, we have wronged ourselves, and if You do not forgive us and have mercy upon us, we will surely be among the losers.” Quran 7:23
If we come to our Lord, knowing we have done wrong, having remorse for our sin and we ask Him to forgive us then He will forgive us.