Ex boyfriend crying to me? Have I made the right decision?

So I've been with my boyfriend on/off again for about 8 months and for the first few months he was amazing and so sweet but after we broke up the first time he just started to treat me like , and lately it got so far as to he practically cheated on me- hadn't spoken to me in a few days and then told this girl we weren't together so kissed her. This boy has a very big ego bare that in mind, he never shows any emotion at all really not even to me. So I met him and said i'm done that's too far and he tried all week begging for me back messaging my friends etc. I finally gave in and started to forgive him so said he could come round. He then cancelled the next day and changed his mind completely telling me to just move on. This broke me I was so upset but that week I kind of realised that I didn't want to be with him anymore and that even though I love him it just wasn't right now. That weekend I was out with some guys and one of them happens to have beef with my ex. My ex messaged me having a go at me for being friends with one of his mates and the guy I was with messaged him back having a go. The next day my ex got really angry at this and I just wasn;t replying, then he started to say he wants to change for me etc. which I just ignored. So today I just decided I needed to tell him how I'd felt and also as bad as it sounds I wanted to have sex with him again one more time. So I invite him round and straight up say I cant be with you anymore its not right I love you but this time i just dont want to, and his face dropped and he just kind of nodded. I kept being like can I have a hug and stuff and he was saying he's confused n stuff so I start crying. He comes over and cuddles me and kisses my head and then we start kissing and end up having sex. I went to clean up and started crying loads for some reason even though I initiated it and i went back and cried to him saying how I wish we could go back to the beginning and stuff and that its so awful and he said that everthing has to end and I'll get over this and it wont care about it all soon. So I get up and am ready to leave and take him home and he hangs behind looking in the mirror so I say to him like youre seriously doing your hair right now and he turns around and he's crying . So i run over and hug him and start crying too because as I said he never shows his emotion and I don't think anyone has seen him cry. We both calm down and I take him back but we're both tearing up on the way back. I honestly feel so heartbroken idk what to do it's awful, i know we can't be together because he's not mature enough but I do love him so much and can't bare the thought of never seeing him again. I just don't get it, as my friend said, we could so easily be together if he just grows up and treats me right so surely he can't love me that much to cry infront of me? I honestly just feel so heartbroken I don't understand if I've made the right decision then why do I feel like this?