WR, Sorry you are under the weather and I hope you feel better soon.
As for calling your h back and letting him know that you told your sons of his call...I wouldn't. I would just leave it alone. You've told them and it's their decision whether or not they call him. Now, if your h calls again and inquires, that's when I would advise him that they were informed. You can't make your sons call their father and he needs to understand this, i.e., that they are old enough to decide whether or not they wish to speak to him. This is his problem to resolve, i.e., relationship w/his sons.
The most important thing for you to do this weekend is rest and take care of yourself.
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.
