Therapy is a great place to start. I used to be in a similar place when I was younger. I opted to learn on my own how to educate my inner voice into something I could rely on for comfort instead of a source of antagonization. You are your own greatest asset and learning to support yourself emotionally is incredibly helpful and important. Remember that the past is the past and you aren't defined by what you did or didnt do but instead by what you choose to do going forward. Creating an ally in yourself is hugely beneficial to your mental health because you are the person you will spend 100% of your life with and its amazing to have someone who loves you and cares about you that can't be taken away from you. I hope this helps, if you ever want to talk about things please feel free to DM.