I have a suggestion that may send a clear signal that you are done and don't want to play his games anymore.
Technically, when he contacts you after you have asked him to not contact you, it's harassment. Your local police can take a report and advise you about a protection from harassment order. He isn't going to be arrested or anything dramatic, but a police officer will likely give him a call and explain to him that repeatedly texting you after you told him not to is a crime.
I know it seems harsh, but getting him to stop contacting you is step one. Its very empowering to be in control of something as well. If you decide to take this step, stick to the facts, leave emotions out of it when reporting it.
This is just a suggestion. I've said before, I can only offer suggestions based on my life experience. This step will deter most people from contacting you again.

I hope you find peace soon so you can work on healing and living your best life.