Safety is a myth

I think things are starting to escalate again.  I've been getting erratic emails from my ex which are mainly just empty threats to take me to court.  He contacted the school asking to see my oldest and then, later, he hacked into my oldest son's tablet.  I'm becoming concerned about him knowing where we live.  I'm nervous.  It's been nearly 2 years (tomorrow) since our separation and nearly 1 year since I moved away with the kids.