Why did my ex start talking to me then suddenly started to ignore me?

My boyfriend and I broke up over the summer. When school started, I did my best to ignore him and move on with my life, but then he started to talk to me online even though we didn't talk in school. In one of our conversations, he told me, "I feel like this conversation is full of love, and what we're doing is not flirting." I said, "All we're doing is making fun of each other, where's the love in that?" He sai,d "Exactly. That's all we did online when we were together. Make fun of each other." The next day he asked me if there was still a chance that he could come over and hang out. I said " It depends. Are you just "being nice" or are you really trying to be a good guy?" He said, "What do you think?" I said, "I don't know what to think." He said, "Me neither." After that, he only talked to me a few times to ask for something. At school, he flirts with 2 of my friends infront of me, but he still stares at me, and when I was absent one day, my friend said he didn't even talk to the girls he flirts with infront of me. He always seems to be near, but he never talks to me, not even online. It's been like that for a week now. I deliberately flirt with other guys in front of him. Last night, we were a a gathering, and even though we didn't talk, my friend said he was constantly looking at me. When he left, he came and said bye to the guy that I was talking to but he didn't even look at me. I just want to know whether he still likes me or if he doesn't.