Assalamu Aleykum Warahmatullahe Wabarakaathuh sister. I ask Allah Subhanahu wa Ta Alla to forgive you for not only that sin that you committed, but to forgive you for ALL your sins, and I ask Allah Subhanahu wa Ta Alla to do the same with all of us who testify his Power, Might, Greatness, and who try their best to obey him, Ameen Ya Zal Jalaali Wal Ekraam!
Anyway sister, I wanted to talk to you about what you did. I think I can kind of understand what you did, but even though, I'm not angry at you sister; Rather, I'm actually really happy, that you came here and expressed your concern to us sister, because it shows that you feel regret from what you did.
I was in the same dilema as you sister. But what you need to do is:
-Regret what you did EXTREMELY (try remembering the GREATEST of Allah Subhanahu wa Ta Alla's blessings upon you, like that he made you a Muminah, Alhamdulillah
).
-Repent sincerely to Allah Subhanau wa Ta Alla (if your repentence is sincere and DEEP, then what happens is that your eyes soak with tears and you start to hate yourself because of what you did).
And also sister, what you have to do after that sister, is that you have to get back on your deen. It's hard to climb up the snowy hill after you slipped down, and it WILL be hard, but through patience, and hard effort, you CAN get back on your deen.
And actually sister, I think that you have completed all of what I said above, Alhamdulillah.
But sister, even though you have, you still feel sad and upset about what you did.
Sister, if you get to the point that whenever you remember your sin, that you fall down (maybe in Sajdah, or with your face in your hands) and cry. Wallahi sister, if this happens to you, then KNOW that you are a Muminah, because ONLY a Mumin ever regrets a sin or shortcoming that they did, and Wallahi sister, you might cry even a hundred times because of what you did, but still, the sin you commited will ALWAYS stay in your memory.
But, if you repent to Allah Subhanahu wa Ta Alla with tears in your eyes (when you remember the sin(s) you did), then THAT raises your status in Allah Subhanahu wa Ta Alla's eyes (and also to that of his angels), because it shows your sincerity.
AND, if you ever want to REALLY regret a sin that you did (so that you start to repent extremely sincerely), then what helps is if you: think about how evil the sin is that you did; remember the favors and blessings of Allah Subhanahu wa Ta Alla on you; and then try to REALLY think about these two deeply (when you are doing Tawbah Salat, or when you are in Sajdah), and then, Inshallah, it will make tears come out from your eyes.
And Allah Subhanahu wa Ta Alla knows best.
