Personally, I don't care who my friends are friends with. My friends took me in when I had no place to go, they are there for me. They also still have a friendship with my ex. Why not? He didn't do anything to them. I have no problem with them remaining as friends with him.
They don't tell him anything about me, and they don't tell me anything about him.
If I understood your post correctly, they came from the U.S. to the country that you are living in, and came to visit you. I guess I can't see how your ex was turning them away from you. I think if he was, (which perhaps he may have) it seems to me that they weren't listening.
My friends are my friends, his friends are his friends, just seems that the circle of friends are all the same, and that is OK with me.
(((((hugs)))))
amy