Struggling to stay away

I know that some people are going to get annoyed by this. I am reaching out for advice on how to stay away from a toxic partner. I am trying to go no contact. I feel as if I hurt him really bad I know he is really upset about losing me. I can’t mentally go back to the relationship as much as it hurts. I know there will be phases of hurt and grief. How do I deal with the things he says to me? How do I stay strong? Any success stories would help or just any advice really. I am truly trying, this is just very difficult. I lost most of my support system due to him.