He lied to Abby when he told her that he didn't have a mother-of-all-secrets but she managed to figure out he has one even if she doesn't know what it is. To be honest, Tony just wishes he could tell someone, anyone he's leading a double life, that he's dating the daughter of an international arms dealer.
But he can't so he has to stay quiet while letting the guilt eat away at him until there's nothing left.
He's beginning to regret getting involved in this operation of Jenny's.
Then again, he has no-one else to blame but himself which only makes his guilt even bigger.
And it doesn't feel like it will be going away any time soon.