You should not try to control what your ex-partner does.
Al is furious when he sees his ex-wife Jean sitting in his favorite coffee shop with her laptop, because she knew that was his spot.
Al wants Jean to not be there when he drinks his coffee.
Al decides that it is too distracting to visit the coffee shop when Jean is there, so he leaves and then comes back later in the day.
Al approaches Jean and tells her that she is encroaching on one of his places and that she needs to leave immediately.
There is no embarrassing or unpleasant confrontation and both Al and Jean are able to continue enjoying the coffee shop.
Jean informs Al that he has no special right to the coffee shop, which she enjoys too, and Al can't ban another person from a public place.