I have the trauma of bullying as well, except my experience occurred last year in the form of cyberbullying. One that lasted three months, and another that lasted several months. One by an ex-friend, another by an ex romantic partner. They both did a smear campaign against me and destroyed my reputation and had people attacking me left and right when I had never done what they were telling people I had done. But more importantly, their gaslighting got into my head. This experience was so traumatic and severe I considered self-harm when it was occurring. I still need to do trauma therapy to heal from it.

I am still waiting to get treatment but I will share some things I have learned in my own research and some things that help me cope:

Write down a list of things you know, like, and value about yourself that come from your perspective and not other people's perspectives.
Learning how to do positive self-talk (it takes practice)
Write love notes to yourself and stick them in places you see daily to remind yourself you are loved.
Read books about healing. I'm currently reading a good one about healing trauma through yoga.
As it was already said, learn to love and accept yourself. And respect yourself. Be authentic.
Learning about boundaries and how to stand up for myself.
Doing positive affirmations has been helpful too.

I think everyone will probably find their own techniques and methodologies and it's important to figure out what works for you personally. Just remember that, no matter what anyone has done to you, you are still a lovable person. And it's possible to move beyond the wounds of being bullied.