Oh, I think that Henry is aware of how that "monster of depravity" part applies to him, but he's still going to keep offering excuses as he can. He definitely has issues with accepting responsibility or admitting the truth.
And yes, I want to wince every time I read Edmund thinking how Mary's questions about Tom show her good heart. He is complete hoodwinked, poor boy, though he has no one to blame for it but himself. He will learn the truth eventually...
"So much easier to believe Fanny will be his salvation than to seek salvation at its true source." -- Very prescient line here.
Thank you!