I think it's her colleague. She smh rescued him at the party?
It's either him or her husband, but I doubt author would drop the suspense of wife and husband fighting against each other that early on.
Ger colleague had all chances to witness her being attacked and it wouldn't be out of the blue for him to kill/revenge against such scum who tried to rape someone he holds in high regard
Are you stuck step-bro~~?
he stuck his finger in his ass