Let me hand out some of my tinfoil and coat hanger antennae...
I'm an IT professional ( well maybe not professional ;-) ), and also have used online dating sites, including some of the more adult ones. Let me try and throw some measured comments on here about what can and does go on between dating sites, albeit only to inform, not to give an excuse. I note he has confessed to creating it now, so I wish you luck in how this turns out for you and the kids.
You would not believe the amount of sharing that goes on between sites. Particularly dating sites. "Adult" dating sites are full of fake profiles created from random pictures trolled from the internet. And once you send something over the internet, you have NO idea on whether it will stay secure. They have automated scripts to do this, and can be very sophisticated so that it is hard to spot a fake. Most are targeted at Men ( i.e. profiles to attract men ) because they are they target market. Some will even use duplicate profiles, shared from other sites within the same umbrella company. I can't recall the name of the site, but I think it came under adult friend finder. Once I signed up for that, I suddenly found that I had the same profile on pretty much every site they owned. This also goes for thing like "Uniform Dating" style sites. Niche interest sites don't have enough traffic, so the owners of such sites have many other special interest sites and they share profiles to look more attractive to customers.
Facebook is not your friend if you care about your privacy. Nor is linkedin, WhatsApp etc... Once you put it on there, you might as well shout it from the rooftop. Don't assume your personal email is safe. I once got a connection suggestion from LinkedIn for my psychiatrist. There was no possible way to link us together apart from one email between him an I from about five years previous in my gmail account. Had I given them permission to use my gmail contacts ? Hell no. I doubt he had either.
Facebook sent me a friend suggestion based on a chat I had been having with a prospective date on WhatsApp. We never went further than talking on WhatsApp, no email, no facebook etc... Fast forward a couple of months, and there she is on my suspected friends list. I actually tried to complain to facebook about it, but that is an exercise in frustration in itself.
So basically, remember two things... Once you click send, you ne longer control it, however you send it ( SMS messages are possibly the safest method for most non tech savvy people, but they still sit on a server somewhere, albeit under telephone company control ). Secondly, you are the product, not the customer of social media sites. Your information is their sales line. They peddle it to anyone with money to pay.
Sorry for the wall of text. This is a pet hate of mine, and this thread threw up some of the usual misconceptions. Honest answer is that people probably aren't paranoid enough !
RLD.