Hello and thank you for using just answer. Have you considered telling him that you only want to be alone with your thoughts and time to process and organize them? Have you tried to possibly write a letter to him as this may help you to organize your thoughts? Taking the time to think about what you want to say is important but also allowing yourself to calm down from your anger is a good strategy and maybe you just need to communicate that to him to help him understand what you are doing and that it is for you and the future discussion you two will have.
You are most welcome. You are doing the right thing but if he cannot understand that, it is on him. Hopefully a letter will make it clear for him and that he cannot push you to talk if you are not ready. I wish you and your partner all the best.