You have to go somewhere you have always wanted to go and not let your ex know where you are, even if you have to move around a bit until you get settled.
Your ex is obviously just as sick as when you left and I hope you have a personal protection order against this person for safety and harrassment. this person is stalking you. Have you talked to the police in depth about what to do?
I know this seems so unfair, but I do agree you cannot put these kind people at risk. They have befriended you and you are right, the ex is not going to stop unless caught in an illegal act.
I am so sorry and wish I knew what to suggest but I do not know what you like to do or work you do.
You have great strength my friend and one more time you are going to have to plan carefully and leave. Please be safe and do not tell anyone, not even the people you are staying with where you are going.
Hugs to you dear friend