HELP ME MOVE ON

So this Thursday, my boyfriend and I broke up. His reason for leaving me was because he doesn’t want a relationship. Yet, I logged onto his Snapchat and he was messaging the girl that I asked him not to talk to Tuesday because he’s cheated on me with her before. Well, he said he would, but instead he changed his passwords on all of his social media and i asked for the password back and he gave it to me, than I saw that he was starting to talk to her. I got angry and we got into a huge argument whenever he got home that night. Than Wednesday, he asked if it was okay if him and his friend go out and I told him it was fine. Well Thursday night whenever I logged onto his Snapchat, he had taken the girl out on a date and they went to the mall, and it turns out they’ve been together since Tuesday night while him and I were still together. We have a one year old son together and he won’t text or call to check on him or get him anything that I tell him that he needs. I don’t want to be back with him because after I read their messages I got extremely angry with him and threw all his belongings outside. Im still upset about the fact he did this to me, we’ve been together for almost 3 years. I just need advice on how to move on from him. He was my first love and we have a child together. PLEASE HELP ME😭