Dear Younger Me,
I would like to tell you to not be so hard on yourself. You are doing the best you can, with the current knowledge you have. By beating yourself up so much, you are pushing yourself down a dangerous path of self-loathing that only therapy will be able to fix. We are all human, and we make mistakes. Accept that and learn from them. It will hurt some of the time, but you will get far more out of it than by hating yourself for not being perfect.
But alas, I cannot tell you this, for you are my past.
What I can tell you is I forgive you. Again, you were doing the best you could with information given to you at the time. While it will be difficult to build your confidence, you can do it. You are stronger than you think you are. It's one step at a time.
I forgive you for all the hurtful things you said. Again, you are only human and you made mistakes. As an adult, I am learning from them.
Thank you for sticking with it. Things could be so much worse.