What should I do if I want to talk my ex on facebook but he and his girlfriend share a facebook?

My ex and I broke up a couple months ago and I just found him over facebook and I want to talk to him and see if he's doing okay. But I think he and his current girlfriend are sharing a facebook. I just want some insight of what I should do and how I should try and start the conversation with him.

Make fake account. Add the account . Say can I talk to your boyfriend(Or say his name) Say i'm his bestie and then on chat say its me