Yaoyoruozu is the 1st of the three to find out. She over heard a conversation between All Might & Midoriya. Her trust in the heroes begins to break.
The first two events of the Sports Festival goes as canon, expect replace the 1-B kid with Toga
Todoroki is next. He finds out during the Sports Festival after he tells Midoriya about his family's s***** situation. Todoroki is furious. He loses all trust in heroes.
Shinsou & Toga won the Sports Festival, but Nedzu refused to let them in the Hero Course per All Might's request. They break.
Kirishima is the last to find out. He finds out after the Sports Festival when Bakugo brags about bullying Midoriya & his friends. He breaks up with Bakugo & starts to ignore Bakugo. (They started dating in Middle School)
Midoriya begins to meet with Hatsume during lunch to stay away from his parents. She finds out by accident when All Might yells at Midoriya for being a failure. Hatsume starts to plan.
TBC...