My partner violated clear terms of our relationship, and I'm devastated

My long distance partner has recently started seeing a girl. He knows because of my past I like to meet people before my partners sleep with them. They could do everything else except sex till I met her next week. He slept with her any way after double checking he couldn't. I'm so hurt I can't stop crying, he came to my city to try and fix things but I'm so scared I can't trust him again. I'm not stopping him seeing her but I don't know how to ever forgive his betrayal. I hate him and myself.

It sounds like this relationship is over. You say you’re so hurt you can’t stop crying, that you’re scared you can’t trust him again, that you don’t know how to forgive his betrayal, and that you hate him and yourself. A person or a relationship who makes you feel like that is not worth sticking around for.

You had very clear terms for your relationship, and he violated them. That’s cheating. Most people consider that a death sentence for a relationship. It sounds like something has been irreparably broken, and the healthiest response on your part is to act on that information and get out.