The theory here is that if you're afflicted by witchcraft, you can't be a witch yourself.  This theory even convinced some daughters to testify against their own mothers.  It's not a bad idea (if you have no conscience), but--sorry--it's too late now.  You should have thought of this idea a few days ago.  Now, your accusation will look like an obvious attempt to distract attention from your own guilt.  The accusation of witchcraft has been made against you and you're still going to have to deal with it.  Pick another option.