I've come back on this after the weekend and see that half the posts have been deleted! For my twopennorth, I think the whole issue with this is that people are unable to give proper comments.
OP I understand how you feel about having someone's dick stuffed in your face albeit virtually. It's a violation and an intrusion and if you had met the man he wouldn't have expected a normal first date, he'd have expected sex right from the off.
I don't think you're stalking. I'd check out anyone I met online by seeing if they were on LinkedIn or social media and seeing if it matched with what he'd said. Did you do that?
I don't know if the postcard was the best means of achieving this but it's done now and it's a shame people can't give their comments without resorting to doing it in a way that is so bad their posts get removed.
In fact I don't know what is the best way of achieving it.
If you'd gone to the police straight away and they'd investigated then wouldn't that be far worse for the wife, children, in-laws, grandparents, those in the family with bad news, those in the family who are ill and all the other permutations that MNetters have mentioned? If he's a faker then it's worse for the innocent party. There's no good way of dealing with it.
Did you check out the wife on social media and see if there are family pictures, children etc?
I can understand why you didn't contact the wife. How would you? Write her a letter and enclose proof (that is offensive communication & the same applies about kids and grandad finding it first, not to mention the husband intercepting and destroying first)? Find her on social media which she wouldn't probably see as if you aren't connected they go into a Message Request folder that I for one forget about and check about once a year. Knock on the door?
I don't know if it is really him, or if he has stolen someone's identity (but if he has he will do it again). If he is who he says he is then he's mighty stupid to give you his house details and address.
If he gave you a phone number you could get someone else to ring it and ask to speak to Bob or whatever his name is and then you could see if it is a genuine number or not if someone else answers.