As kind as you are trying to be, it’s not beneficial to you, or him, to continue communication now. You are the #1 priority now. I was in a very long relationship, and engaged to someone who had been my best friend for many years. After a lot of pain I ended the relationship and he would contact me on and off, telling me things like I was the only one for him, he would always love me, and other things that were just torturing me.
When your gut (or whatever part) tells you something is off, something isn’t right, and you listened and ended the relationship, you need to follow through on that. It’s really great you value him and wanted to have a good relationship still, but he is emotionally manipulating you and causing you pain. You cannot properly move on, grow and have peace when he keeps trying to burst back in with talking and then launching in to fights.
You need a clean break, which means NO contact of any kind. As other PPs have said, I would let him know that you understand he is hurting, and so are you. You need space to focus on you. Ask him to refrain from communicating with you in anyway, and that if and when you are ready to speak to him, you will reach out. I don’t think giving HIM a time (like 6 months) is a good idea, because he might try to argue less time, might just think that means you WILL come back after that and you really just wanted a “break” from him.
I’ll tell you now, based on what you have shared, and my own experience, he may not take this well. You may very well need to block his number, his emails, block him on social media, tell friends and family to not speak with him or share information (if he continues to try to talk to you or get info about you or to you through them). I would tell my ex: If you respect me at all, please do not reach out to me. I need time for myself. I will reach out to you on my own if I decide to.
Stay strong. I know it hurts, and it hurts to hurt those you care about. But it’s time to focus on you. And while it will hurt him, I am sure this will help him more as well.