Overwhelmed with guilt from a major sin, how do I know Allah will forgive me?

Remember this, no matter what the sin, no matter how big, how many times, day or night, past or present, Allah says that He wants to forgive us. Allah says that He loves to forgive us. Allah says that He promises to forgive us. And it doesn't matter what the sin is. Allah is there for you. وَاللَّهُ يُرِيدُ أَن يَتُوبَ عَلَيْكُمْ Allah says that He wants to forgive us. Allah is calling us. وَاللَّهُ يَدْعُو إِلَىٰ جَارِ سَلَامٍ He's calling us to Jannah. In fact, the Prophet Muhammad ﷺ said in Adi Nisa'i Muslim, that if there were people that did not commit sins, Allah would remove these people, would remove us and replace us with people that committed sins just so that they could turn back and ask Allah for forgiveness. This is how much Allah loves it when we turn to Him for forgiveness. Yes, we're all human. Yes, we all make mistakes. But it's one of the tricks of Shaytan that makes us feel that, you know, there's no hope for us. That's one of the tricks of Shaytan. The Prophet ﷺ was always an optimistic person. So whatever the sin, never despair. Allah is there. Allah wants good for you, Allah wants