How do I get closure from a bad breakup?

I was with this guy for a year and he was not only my boyfriend but my best friend. I was in love with him. We both go to the same school. About 8 months into our relationship things started to go a little downhill. He definitely started to let up and wasn’t putting in as much effort anymore. Yet, I was still trying to so hard to make it work because I knew we had a special bond. He still told me he was in love with me but I seldom saw that because there was barely any effort from his side. He hardly planned special dates. I mostly planned everything from then on. I had to work so hard and this was where a majority of our fights came from. It was the week before the start of summer and he was going away for the weekend. He completely ignored my texts and phone calls which wasnt normal. That Monday morning at school he acted as if we were not together anymore and that I was a complete bother to him. So after many red flags I confronted him and said, “So are we basically done?” and he responded with, “Yes.” This really bothered me cause I feel like you cannot end a one year relationship without even sitting down and talking it through one last time. Then I said, “When were you planning on telling me we were over? We’ve been together for a year and this is how you want to end it?” and he said, “I am not going to make a relationship work thats not working. I don’t like you as much anymore.” He then walked away and I havent heard from him all summer. Not a word. I feel like I got ZERO closure from this. It was incredibly hard to come to terms with the fact that this guy I spent so much time with was not there anymore. I still dont think im over him completely yet I want to be over him! I need closure before I have to go back to school in 2 weeks and see him. I feel like it will be completely awkward and hard for me. I feel like the only way I can get closure is if I contact him and just have a civil conversation with him because I have this knot inside me full of fear of that first interaction with him after so long. So tonight I texted him asking how he has been this summer and I got no response. Should this be a signal to just not waste my time anymore on him? I am having such a hard time letting go! What should I do? I feel better that I texted him because I feel like at least I put the ball in his court and got the weight off my shoulders. How do I get closure from this type of break up when it ended very unclearly?