When does the creature realize that he might be a "monster"?

I think probably when the cottagers try to kill him.

He realizes that he's different and might be a monster toward the end of the chapter. He comes to this conclusion after watching the cottagers and seeing their sense of family.

"But where were my friends and relations? No father had watched my infant days, no mother had blessed me with smiles and caresses; or if they had, all my past life was now a blot, a blind vacancy in which I distinguished nothing. From my earliest remembrance I had been as I then was in height and proportion. I had never yet seen a being resembling me, or who claimed any intercourse with me. What was I? The question again recurred, to be answered only with groans."