Hi

New to this forum and looking for some support, wisdom and agreement that my ex partner has undiagnosed adhd. It's all very sad, especially as it's given me the wake up call I'd like to try and make our relationship work but he doesn't want to. 
Background, I'd been with him for a little over 2 years, I'm 46 no children and he's 47 widowed with 9 year old twins. Was very attracted to him from the start, my sister when she first met him immediately thought he had autism, which he later on in relationship agreed with though no formal diagnosis was ever done, and one of his son's has it too. 
After spending majority of lockdown with him and kids, I eventually noticed how chaotic and messy his house was, you couldn't tell the cleaner had been as it was just messy! Though I thought it was just a single dad struggling. His work in IT dried up, when in fact IT work has been quite plentiful. He is not driven to find work, he is mortgage free and his mum is giving him money monthly to help. My sister tried to help him with career tips as she worked in recruitment, she said it was 2 weeks worth of work improving cv etc, 8 months later still not fully done, lack of attention. So basically he spends his day going for bike rides, meeting up with widow friends for walks who he says are his support network  (often female, a few he's slept with) and doing the bare minimum in house and in search of work, reads Reddit, looks at a bit of porn.  I have since developed into a nag, I had to nag him to get his tiny car valeted as it was so dirty inside, cost him £60 as it was that filthy. He says I get cross all the time and tell him off if he doesn't do loads of jobs, my other negatives is I've cancelled on him several times when I've been too tired after work to go round as I know I'll be sat in his messy house, I've also ended it several times as I've been cheesed off, but we've always ended up getting back together by the next day. Immature of me. 
He also loves cricket and basically over the season bizarrely messed me about with numerous plans on cricket days, to the point I felt overlooked and ignored.

Alongside this, we've still enjoyed an amazing sex life and both wanted to live together, the issue being how we would do this, as I don't like his house and layout of it, and that he makes no effort. I get the picture his deceased wife did everything in house and garden. 
 

The thing that ended it was he can hyperfocus and he decided to do this with my attractive friend who does enjoy his banter (which I view as flirting from him but innocent from her) I also heard him talking to her about a post he put on fb about grief, this made me angry whilst although he lost his wife and went through something awful he shows zero empathy to anyone else , and said to me once perhaps it was a good thing she died as they didn't get on. I see that he posts these things for attention from women rather than being genuine. So after months of frustration we had a huge row and he said it was over, that it was his turn to control things. He has since gone extremely cold and not given me an inch even when I suggested counselling and said it's over. I feel devastated as I would be willing to give this a go as I still love him immensely and feel heartbroken, we've gone from speaking about 5 times a day and seeing each other loads to zero!
 I'm assuming he has adhd as he ticks every symptom including reckless driving at times, would you agree? 
How can he go from telling his kids I'll be moving in shortly to 2 weeks later ending it.  From your experience do people with adhd mean it, I guess I should move on, he was so calm when he ended it, like it didn't bother him at all!