Hi Sunny, this does not sound well.
I think it could be:
"I knew you were a dishonorable and inglorious man, uncle, but not to this extent" (I already had that opinion about you, but never thought that it was that much)
or
"I know you are a dishonorable and inglorious man, uncle, but not to this extent" (that's what I think about you, but I can't believe it's that much)