How can I heal from this? Was I wrong in my reaction?

I had been seeing this guy for about 6 weeks. Him and I had a history prior to this for about 2 years, and I think he knew my feelings for him had never really gone away. Things never ended well between us before, but he reached out to me again 6 weeks ago asking to be friends. However, we weren’t really acting like friends. We were having sex, and he would tell me he loved me all the time. We would talk every single day, too. I however knew he didn’t want a relationship with me because we had that conversation. So, on a day that we had plans to go out to a party together with friends, I told him that I couldn’t keep being intimate with him because it was hurtful to do so whilst knowing he doesn’t want to be with me. He was understanding and we ultimately agreed we’d stay friendly with one another and still go to the party but keep our distance. Shortly prior to the party, he called me to let me know he’d be bringing a “friend” to the party, meaning a girl, and asked me if I was okay with that…? I got extremely mad and told him that that was super disrespectful of him to do so. It ended up in a huge fight and I ended up spamming his phone and insulting him a lot. I felt super bad about it and suggested we talk on the phone to mend things with one another. We spoke over the phone and he was being so harsh to me the entire time. He was extremely opposed to mending things with me and basically told me that him and I were not exclusive and that he was allowed to bring anyone he wanted around me, especially since I had “ended” things with him. He told me I was an unstable person who made a big deal out of everything, and that I was absolutely not the type of person he’d ever want in his in his life. I ended up hanging up on him and just blocking his number. I feel horrible that we went from having fun together to him essentially hating my guts and wanting me out of his life. I also feel horrible for insulting him and spamming him.

How can I heal from this? Was I wrong in my reaction?
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