He should feel ashamed simply as he tried to rape her. No proof of innocence required to feel sorry that you attempted to rape a woman. Whether Sahiba hatched a plan or not changes nothing, him attempting to rape Seerat would be equally bad. His only excuse would be he was under influence and a person with little bit humanity will curse himself for such a thing. And he is supposed to be a damn good human.
Even under alcoholic influence is not a reason to attempt such heinous crime. To have alcohol was his choice so no amount of justification will work