I really don't care what you think. I care what Jesus Christ thinks. And Christ clearly made His thoughts known on the indissolubility of the Sacrament of Marriage.
I totally agree with that.
However, we don't know that grave matter exists in Pope Francis' actions (e.g. it would be grave matter if he were supporting the supposed "annulment" of valid matrimonial vows); and we don't know if full knowledge and full consent to that exists (if that's in fact his intent at all).
So --- even in view of the undoubted fact that deliberately declaring valid vows to be "null" wold be grave matter--- none of the three conditions for mortal sin can justly be assumed in Pope Francis' actions. That's why the adjective "corrupt" can't be justly applied to Pope Francis personally.
He may be making an appallingly imprudent decision to amend Canon Law in this way and at this time, but impudence in itself is not a sin even if it is a destructive mistake.