Beatrice, I wouldn't have been too happy w/him calling my number, especially when I didn't provide the number to him. Is your number unlisted/unpublished?
I think he called your number hoping that your son was there. He knew that if he called your home, your son would speak to him. I think the man is playing games and I do wonder what is behind it all.
I understand how your son feels and until your xh can walk the talk, I wouldn't trust him either.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.