I have a peculiar question.
Take no offense, but you're quite a bit older than him. And I'm sure as a parent, you'll understand I'm not wishing you ill when I say I hope you pass before your son. And if and when that happens, what'll happen to your son? You said you had begun falling for each other. This seems to me like perpetuating a cycle. First, you had to suffer through such a loss and in the future, so too will he. I don't see much good coming out of that in the very end.
About your relationship here and now though... Good for you, I guess. I'm not a mother, nor even a woman; but seeing as everything happened perfectly consensually, I cannot say anything negative about it. Best wishes to you, and thanks in advance for the response. Good day.