WHO THE F CATFISHES A OLD MAN

So my fiancé’s grandfather has been talking to this woman on plenty of fish for about a year, we told him many times we thought she was a catfish as it’s happened to him before. He has gone to meet her 3-4 times and no one showed and he would get home and her profile would be gone, so he emailed her to say “wtf is going on” he got a email this morning saying she is indeed a fake, it’s a group of women looking for cheaters and gift giving kind hearted people to leech off of. She some how knew things nobody else knew, she knew exactly where he lives, knew about us and our children, knew how he acts around our son, knew where we all go for lunch... knew about his family that are passed.... so she must be ether a good hacker or someone who was once close to him.... anyone know anything about stuff like this???!! This poor sweet old man is heart broken! His wife left him about 12 years ago for another man and was cheating on him and this is his first time trying to move on.....