What do you do when your ex is stalking you online?

What do you do when your ex is stalking you? What should really be done with when your ex turns into a creepy stalker, lurking in every post you make?    NOTE FROM MAXINE: We joke around a lot but we're very aware that this is a serious issue. If you do feel like you are being stalked by ANYONE, not just an ex and you feel like you might be in danger, please do not hesitate to gather as much evidence as you can and alert the authorities. Go to https://www.stalkingawareness.org/what-to-do-if-you-are-being-stalked/ for resources.