Meet him for a drink somewhere you can easily leave from and pick one:
“X, I’m sorry, this isn’t working for me. We need to break up.”
”X, I’m sorry, this isn’t working for me. I’m going to look for someone younger and more virile.”
”X, you’re obviously not in the right place for a relationship with me right now. I need to find someone who actually fancies me. Hope things work out for you.”
”X, This clearly isn’t working for either of us. You should go find someone you want to sleep with. And I need to find someone who wants to sleep with me.”
If he tries to talk you round and succeeds, do it again the next day over text. Add “Please don’t contact me again.” Then immediately block him on all channels.
Edited to add: Actually, given your last message. Just do it by text anyway and block. He isn’t just in the wrong place, he’s punishing you for not being his ex. It’s nasty and cruel behaviour and will escalate and destroy you if you stay with him.