This really is on the same level as stalking. While, keeping a record of text messages is a good idea, if she is interfering in your life with calls and texts, changing your number could be one small thing you could do to cut her off more. I understand your fear of retaliation. At the same time, I think there must be enough people to see your side, that you'd have people who would stand up for you. Sorry to hear you're having to go through such a hell of a situation, with your boundaries being constantly crossed. It seems like you've been given a lot of good advice and I hope it ceases soon.