If he should manage to put something in motion and your name is on the deed, they will not be able to go through with the refinancing without your signature. Keep a close eye on his and your emails to make sure they don’t send you a document to e-sign. If he’s clever enough he could electronically sign your name. E-signing is just typing your name on the document. If any company sends you documents, send them a registered letter explaining the situation and cancel the refi.
Turn off the ringer.
Child lock the computer so he cannot get to the internet only to games.
they will give you a password...make sure you put that info somewhere safe because you cannot unfreeze it without knowing that.