A simple question about relative clauses

I just don’t have a good reserve of names of parts of speech, so the question may be quite soft-ball.

I mean to say, "I am the only idiot in this world."

Now I want to convey the same meaning by saying, "I think there is only one idiot in this world, who is me"

Is the sentence grammatically correct/well-formed? I reason that the relative clause is modifying "only one idiot", rather than "world". But I do realize that sometimes the relative pronouns should modify whichever is the nearest (I would appreciate it very much if someone knows what’s the name of this rule as well).