Dear Mr. Jalaal,
Your son is already very lucky to have a father like you , willing to co operate with him in a tough time like this. After a break up family support is the most important thing , to make him feel loved , wanted and most important boost his self confidence. Please remember with a break up like this , also comes low confidence and a sense of rejection which becomes the root cause of depression. Without him knowing please give him as much family love , care and make him feel wanted and important , give him space if he wants to be on his own for a while , make family plans with your children and grand children , ask for his suggestions and advice for family matters , discuss your work problem , praise him for his valuable advice in matters like these.
It takes time to get over a person , and only time will heal the scars . There will come a day when he will not even remember this time.
All the best!