Hey mate! I think I've been chatting to you on Reddit (re: chat)
I'm feeling for you mate, and I know what you are going through. Don't worry about her feeling happy about having her own flat, the reality of her situation will dawn on her sooner rather than later. From my experience, my WW had set up a new rental - all while having her philandering AP over in front of my kids. She told people she was happy, but the kids told me apropos of nothing that she spent the first few months crying in her bedroom regularly. When I finally announced I was seeing someone (8 years my junior haha) else about 8 months out, she took a month off work and went off the grid for a week to 'find herself'.
So what's your ex-wife's end game? As you mentioned, she's picked up a serial older cheater who evidently thinks nothing of trying to sleep with younger subordinates. Once he moves on to the next shiny thing (and he will), she'll be left fending for herself financially and emotionally. She'll dip her toe into the dating market only to find that no one will have an interest in her outside of attempting to sleep with her. The kids will grow up, and by weight of statistics, at least one of them will resent her when they ultimately find out what she has done. She'll struggle to stay connected to them, especially when they realise that you have been the stable one; the one that kept the household going and protected them. The one that endured emotional abuse and betrayal.
Meanwhile, you'll have met someone else. Someone to whom the idea of cheating is utterly repugnant. It's not a smooth glide-path, and you will have bad days. But you'll also have awesome days, and at some point the awesome days start outnumbering those bad ones.
I am glad you are seeing a therapist/IC, that is utterly invaluable. Hit the gym to make yourself look and feel better. I hope you are keeping well regardless mate.
[This message edited by Hurthalo at 9:50 PM, Thursday, May 4th]