I didn’t manage to read your original post but have spent the last hour reading through all the comments here.
Like many I’ve been through what you are going through right now and it’s tough, toughest thing I’ve ever had to deal with.
Firstly you are doing absolutely the right thing of going no contact, your son is grown up and is not related to your twat of an XH so you don’t have to do the co-parenting that many of us have to cope with. I would add that if you do have to have contact with the XH adopt the ‘Grey rock’ technique..polite but business like and show no emotion.
The speed in which he’s discarded you and moved on so quickly and his lack of empathy is so very familiar. There’s a lot around on the internet about narcissism and narcissistic personality disorder (NPD) and the links that has with cheating. It took me a year or more to finally realise that my ex displayed some strong narcissistic traits, and the main bit of advice I received from my counsellor to dealing with these types was ‘no contact’.
The scary thing was that she explained to me about narcissism, she couldn’t say whether or not my ex had a full blown personality disorder but she certainly said that they come in many shapes and sizes, male and female, overt and covert. They thrive off attention, both good and bad. It’s like a drug to them, they need a supply and when they have their shiny new supply (ow) they no longer need you (discard). They may well be a backlash at you in the future, he may provoke you into a response, your instinct will be to defend yourself..if that happens keep being your dignified self and don’t react, maintain no contact. Have a read about narcissism, it was a true light bulb moment for me and enables me to know what I was dealing with and how to deal with a disordered person.
I would also recommend a book called ‘leave a cheater, gain a life’ by Tracey Schorn aka The Chump Lady. //www.chumplady.com read her blog, join the forum it’s been a great help for me.
Keep doing what you are doing, the bad days become less and less over time, keep your head held high and look forward to a cheater free life.
X