Forgiveness is a process. In order to forgive yourself for your own past, it will take more than one day, and sometimes even more than one month. However, it doesn't matter how long it takes you to start with a clean slate - the main thing is that you really want it.
Look, we've all made mistakes. But what is important is exactly what conclusions a person draws from a problematic situation, and how he decides to live on. Even if you made a serious mistake in the past, there will be no benefit from tears, constantly recalling the situation, "rewinding" events to understand what exactly you did wrong. If you constantly blame and punish yourself, you will never be able to feel like a complete and happy person. It will only drown and destroy.