So when did he realize that Pati is Patricia and what exactly made him realize that?

I think he knew from the moment he saw her, and come on, Pati? Like that's a nickname for Patricia. He's not dumb. He very well knows the capabilities of his magic better than anyone else. So I'm sure he had an inkling and then it was pretty much confirmed when he saw her. How could he not recognize his true love?

Of course it's obvious... but while reading, it felt like he believed her to be a double ganger just like her family did (￣∇￣"). So I still would have loved to see him say something about it.