OP, exh also stalked me along with Jo's new girlfriend.
He moved in with her within 12 weeks of apparantly meeting her. I dont think he was seeing her when we were together. But he started seeing the week the house was sold, apparantly, and loved in 12 weeks later.
She helped him stalk me giving him access to her accounts. Problem was that occasionally a very old post would be liked. I still dont know if it was him or her and if it was by accident or on purpose so I knew.
He even followed me in his new business name. I could spot it was hom a mile off.
I also gave my vintage car to my dad and purchase a new cheapish run around. Just incase it had something on it.
The only reason he stopped is because I met and started seeing dp. He is 6 ft 4in and works in security and is huge. Dp is actually far more laid back and kind than exh, just looks like he stole grumpy cats expression most of the time. 
Exh is terrified of him. It's awful, but that's the only thing that stopped him.
I hardly use social media anymore. And definitely dont check in anywhere. I am convinced that some of my facebook friends update him. But no clue who.