Is it that she has possibily slept around in the past or currently sleeping around that bothers you.
If its the former, well we all make mistakes. I guess you have to decide if she really was sincere when she cried or she's just playing you.
I know plenty of people who got wasted one night and went with someone they regretted the next morning. Being intoxicated can bring out the worst in us. I would guess if that was her only time then maybe you can dismiss it. However, this isn't some innocent naive girl either, your average Chinese girl isn't gonna ask someone she just met to stay over.