Feels like a threat...what should I do


Ex said this just now. I do feel threatened by this. Feeling a lot of stress.

What would you do if you were me?

Backstory; ex husband messed with drugs, I have full custody, he's went almost 3 years without seeing our son. Suddenly wants to see him, mad because our son sees a specialist on a specific weekend (made months prior to him EVER asking for him). I don't message him usually because he insults me and tries to fight constantly