Son has left wife and two small children- devastated

Out of the blue I got a phone call from only son aged early 30's to say they had split. Children aged 2 and 1, amazing DIL wonderful mother to children. Appears pressure on him of two children close together, small house, self employed trying to build a business caused him to in essence not be able to cope.

Text book reasons came out, grown apart, physical relationship non existent, tried to raise it but not really discussed i think. Fly in the ointment, his business involves working with clients who are mainly ladies that lunch. Appears he is in a relationship with someone 19 years older than him, plenty of money, big house, big car, time to drool and boast about a trophy goodlooking, fit lover. Her previous conquest was her gardener apparently. She is a widow.

I could say more, don't want to sound bitter. Can see for him the oasis of the new relationship in the quagmire of the daily grind. As his mum I love him and want to support him, I am appalled, devastated, disappointed etc that he can go live elsewhere, not with the woman just yet, and give me a pile of crap about co-parenting being an amazing opportunity, the children won't lose out etc. From what I can see he never, but niether did my DIL , TALK, about their issues before he opted out.

I am talking to both of them, son very difficult, deffensive appears to have no remorse. A departure from the mature, caring family man i though he was and has appeared to be, genuinely.

I know I have to cope with this, offering support to both, my DIL is a truly lovely girl, she too is devastated. I can't sleep, eat, try to get to grips with it but all I can see are those dear children's innocent faces and it tears me apart.

I am not the first to face this, but it is the first time for me, any comments gratefully received.