I'm gonna second this. He stalks because it works. It scares you into contact. That gets you under his influence (and I know these guys are charming).
You leave the relationship. You go no contact. He stalks, stalks harder, pushes more, there will reach a crescendo of some sort, when that doesn't work the stalking stops and you are discarded. What I think you're trying to avoid is that crescendo. You can't. You just can't. It's almost a shame that we can't shoot these people when we leave them and save us that dangerous game. But it is what it is.
Mine did the calling, texting, etc. I cut him off. Blocked him. He showed up at my house and sat outside refusing to leave when I wasn't there but my daughter was. I then did unblock and call him and tell him to leave. He managed to convince me to let him say goodbye to his dog. I caved, thinking this could be closure for him and he'd get past this because surely he did love our dog. He came over, crying, spent 1/10 of the 20 minutes I allowed paying attention to "his" dog and spent the rest crying at me for leaving and asking to be friends. I told him to leave and not to contact me. Re-blocked. He didn't come back to the house, surprisingly, but he did get through some online communication (can't remember what social media site now) to threaten me with legal action over said dog. As if he had a lawyer and a case. It was all I could do not to rise up in a rage and breathe fire all over him, but I resisted. I kept blocking and waiting for him to show up all aggrieved and feeling victimized or steal my dog when I let him out in the backyard to pee. I watched that fence like a lunatic for a while. Haven't heard from him since.
Luckily for me, his crescendo was threatening to take my dog. I know that sometimes the crescendo is murder. I know why you're frightened. I married a gentle sweetheart (ha) and I had a gun because I was worried. Mine was a crack addict and you do not ever know how they will behave, no matter who you thought they were before. You will live like this until you let it play out with no contact and let the final stanza of his crazy reach it's high note and then fade away. When it fades, you get your life back. If you're afraid that he's going to potentially kill you, you really should contact law enforcement.
This game SUCKS, but there's no way around it. All you do with grey rock is to delay it and intensify it when it happens.