I Think We're On Different Paths

Well done in recognising something didn't seem right and/or it wasn't what you really wanted, then following through with the Dear John letter.
If he was a genuine person who lived near you, he would have wanted to meet up before saying he loved you and thinking of you as a possible partner. He would surely, also, have wanted to see how you got on with his son as well.
It does have all the hallmarks of a scam - so similar to the stories on TV etc.
He's not done anything illegal if he's simply used a fake profile but not actually asked for money or gifts . You might want to contact the dating site, if that's what you used, to suggest they check it out as you're not sure it's a genuine profile - it would no doubt be breaking their rules.
Beware possible contact from other scammers as, if he is a fake, he could have passed some of your details to other chancers ( not necessarily re dating but maybe finance deals or investment opportunities etc that seem too good to be true).
You sound like a warm, kind-hearted person who didn't want to disappoint this man ( if he was real). Stick to your guns about what you're looking for in a relationship and, whether the right person comes along or not, I'm sure we all wish you happiness and fulfillment in the years ahead.

some years I was approached on Instagram by a man with a very similar scenario to this, same age son etc. He said he had togofor anengineering job in Nigeria. Of course I'd latched on tothe fact that he was a scammer sometime earlier, all the spelling mistakes and repetitive love messages,so I thought I'd see how far he'd go. Soon he was asking for money for a failing project in Nigeria and saying his son needed to have medical treatment. So I pleasantly said' Don't worry I'll bring the money down to Nigeria and meet you at the same time.'. rather predictably I never heard from him again... You could play it out maybe?