Please i need an honest and blunt answer

My ex and I dated for two weeks, he was loving at first even though he knew sex wasn't included in the relationship, he accepted but we make out. Once in a while.

Now he brought me home once and unfortunately his ex and I both lived in same building. He dropped me off and I noticed he was talking to a lady, I ask who she was and he said his ex, I was furious because he knew all along we both lived in same building but never told me, instead he always says he has a friend who stays in our building but he never mentioned her all along. I asked him what they were discussing he said she wanted to see him about something but I told him that is disrespectful to me since she knows I can see them both talking beside the apartment. He pleaded with me to allow him see her, and promised to tell me what they discussed so I obliged.
He later told me she complained of him not picking her calls, that she has been calling lately, I was pissed for he didn't tell me about it till when I saw them talking , immediately I recalled a time I was at his place he once spoke about how she wasn't at fault for cheating on him with her ex because he never had time for her , so he caused her to cheat. Immediately I felt nauseated for he took sides with his cheating ex but I didn't utter a word. So we settled it.

But that same day he saw his ex after he left my house , he removed my picture from his profile and left it blank, and since then he has been distant. So we broke up because he kept on saying he doesn't deserve me, I deserve someone who would treat me as I want because he doesn't think about me when we are apart. I didn't talk to him neither did I picked his call for a month and one week, only for him to show up at my house that he has missed me, but we are friends now so he came to say hi

I didn't allow him into my room so we went outside and he started putting blames on me that I made him tired of me because I complain too much bla bla bla

While talking his ex came out and he said I should give him a few minutes for he wants to see her, immediately I told him I have to go, then he said he's going to call when he's done talking to her for two minutes but he spent over three hours with her and then went home, without seeing me, now I hate him so much and I think he came for her not me but he actually wanted me to know he now sees her just incase I bump into them since his ex and I his current ex share a building

I hate him so much now, why did he do all of that, this was the same ex that played him but he still sympathises with her and I need an advice on how to treat him like the jerk he is since I know he will be visiting her often?.