I had to shake my head. He's just going to continue to try different angles to get into your life. If the friend request was bogus, the person posting it to you should know better and should know that you are checking things out.
I hate to say it, but your xh is very jealous of you and your life. He's a very unhappy camper no matter how many times he says he is happy. Poor fool. They never think we will move on and once we do, it's too late.
You did the right thing....keep your eyes and ears open because he's not done yet.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.