Is there a term for the rhetorical device of making a statement by disguising it in the context of saying that you will not in fact make such a statement? I'm thinking of a politician announcing "I will not stoop to calling my opponent an adulterer" and, in effect, doing exactly that.
Apophasis is exactly what you seek. To borrow the definition from Chambers, it means "effectively saying something by stating that you will not mention it."
It is a commonly-used word in theology: a description of God is apophatic when He is described using what He is not.
EDIT (adding another answer after FumbleFingers' comment) - Paralipsis. Once again borrowing Chambers definition, "A rhetorical figure by which one fixes attention on a subject by pretending to neglect it, as in ‘I will not speak of his generosity’, etc." I concur with FF that this is a better fit than Apophasis for OP's question.