Yeah, I thought so too. The "real" Don finally showed through...the one who was terrified of his past and of being found out.
Is he terrified of being found out? He's obviously embarrassed and ashamed of things he's done and where he's from but being outed at work was hardly a big deal. That leaves his personal life. He's a ****** husband and doesn't seem to be much better of a father. What's the downside to Peggy uncovering his past? She leaves him? His life (as he's decided to live it) would get better.
lefty