mistaking my sister-in-law for my wife after getting drunk!

On the night of his marriage proposal, Xu Yang was dumped by his ex-girlfriend.
Feeling heavy-hearted, he went to a bar to drown his sorrows.
He didn't remember much about what happened that night, but he woke up with a stunning beauty lying next to him. At first glance, she looked somewhat familiar.
Wasn't she his ex-girlfriend's sister?
And it seemed like she was about to wake up!
What should he do? He's anxiously waiting...