exactly, if you confront her. She will likely just drop him and spare herself the worry/hassle. She also will NOT tell him after 3 months. You have already made up your mind on what your going to do, just needed validation??? Don't make this more drama filled then it has to be, you don't have to meet her. Just get reception to pass her a sealed note and leave.
I saw you again, my cousin is a great guy. He's got a heart of gold and I love him like a brother. I would never say anything to him but I hope you don't break his heart either. I sincerely wish you guys the best.