I remember telling my therapist how fake it felt to try to feign positivity and reframe my negative thought processes in some positive way. She told me it's not about positivity. It's about reframing things in a more REALISTIC and PRODUCTIVE way.

Would you ever speak to a friend or even a stranger the way you've been speaking to yourself? Probably not. So why do you you think it's okay (or natural or realistic) to be so cruel to yourself? (is what she said to me)

Furthermore these negative thoughts processes have outcomes that are preventing you from living the life you want and achieving the goals you set for yourself. You need to approach your thoughts and feelings in a way that moves you forward toward actions that create the outcomes you want in life. Reflecting on mistakes, circumstances, etc. is important and useful, but can easily turn into rumination and leave you stuck rather than push you forward.

Beating yourself up, looking for scapegoats, ruminating on your mistakes, etc. is not a productive use of your mental energy and will not result in actions that get you anywhere you want to be, which creates a cycle of bad results, thoughts and actions that will keep repeating until you start retraining your brain to approach things in a productive way that produces the results you want. It's not an easy or quick change however and requires constant work (starting off with small steps), just like training a set of muscles or changing your posture. Your brain gets wired to work a certain way and rewiring it takes lots of repetition.