Obviously, no one knows what happened but the two of you, but you have a lot of people who followed you on this journey who I know feel that you did, indeed, try SO hard - and under really, really shitty circumstances.
I think the lesson you taught your son in this is far better than the one you would have taught him had you stayed.
And I just want to take a moment to acknowledge your palpable relief, joy, and fulfilling solitude. The way you described it was so buoyant, I felt like I was floating. Enjoy every second of that. You listened to your heart and that's always the right choice. I'm so happy for you.