Right now Mel has not denied that the tapes are authentic, and there is only speculation (which you apparently wish to accept whole heatedly) that there was any tampering of the tapes.
Gibson has said nothing. Only his attorneys have. And they have said he only asks that this not be played out in the press. She has other ideas. There can be only one reason that she would release tapes to an online gossip site after a judge sealed them with a restraining order. And that reason is to humiliate.