I had a break up when I was 20 that was the worst of my life.
I'm late thirties now and my partner (who I loved enormously) walked out on me and my kids a year ago without a word or any sort of warning and never came back.
Still, the break up when I was 20 was worse.
It was worse because I completely believed he was "the one", the only person I could ever love that way (we were together 4 years) and I felt like life would just always be a bit worse.
I cried a lot longer than 5 weeks. I was still crying about it until perhaps 5 or 6 years later and I still felt pangs for even longer than that. For the first year I barely did anything.
People expected me to get over it a lot quicker than I did, and they withdrew sympathy and support so I stopped talking about it. I just kept it inside but it was still there and I acted out with the wrong crowd, drinking too much, experimenting with drugs.
To be fair though, I wasn't wrong.
It took me 15 years to meet someone I loved as much, so the love I felt for him was very deep and very real despite my young age at the time.
Funnily enough, I had lunch with his sister yesterday and she says he still regrets letting me go and feels much the same way I do....that it was the best relationship of his life.
What I am saying is that it can come at any age and just because he is 20 doesn't mean he feels the pain less...perhaps he feels it more.
Bear with him, he will feel better. Le him cry as long as he needs to. Don't make him feel like he "should" be over it. The key is mostly distraction and finding successes in other areas. Don't try and convince him there will be other girls, or patronise him by telling him he is young and only starting life.
I wish I could give him a hug. You sound like lovely Mum, he will be thankful for that x