Should I inform him we are done??

So there is this guy I've known for 4 years now. We broke up for 5 months. Than started talking again. He said he wanted to give us another try. He admited he was seeing someone but that if we went on a few dates and things worked out he would drop her. I know it sounds like a load of crap, and I called him out on it. But I was the reason things hadn't worked the first time. I didnt cheat or anything like that, but he claimed I broke his heart. And basically quilt tripped me into accepting. Whatever things were going well until he mentioned the other girl which pissed me off cuz we had been to a few dates and had sex by than. We got into a fight which he talked his way out of claiming we were casually dating we werent serious yet. I know Im stupid! Anyways we went on dates regularly texted often and spoke on the phone every night. That completly stopped a few weeks ago. No dates No phone calls and rarely any text messages. He'll text "Good morning babe" than not text me again. If I text him he'll replie two three hours later. I asked him wtf was up he claims he's stressed. After that I didnt hear from him in two days.  He just hit me up asking if Im ok cuz I was acting a little off last time we spoke. Honestly Im done, would it be bad if I just never spoke to him again and left it at that. Or do I really have to be an "adult" and inform him he can go fuck himself? I know is my fault and Im stupid for falling for this shit. But we were best friends I honestly never thought he would do me dirty...