Should I stay with her?

I have been dating my girlfriend for a year.
She is an amazing girlfriend. She loves me very much and does everything for me. I can tell she adores me. And I love her very much too.
But recently she told me a few things that made me think twice about us.
She told me that 3 weeks after we first met (We had sex the first night we met and we talked everyday on the phone after that). 3 weeks after we met she had sex with another guy. She said she was very drunk and the guy was too and was a stupid thing that happened. She insists in telling me that was not cheating because we were not completely official at the time.
She also told me that she that kind of sex doesn't mean anything to her because she had sex with 23 guys total (she is 22) and this fact is the thing she is most embarrassed about her life. She told me she was young and stupid and this fase is over.
I know she has been an amazing girlfriend for the past 6 months and I couldn't ask for anyone better. But this new information and how she didn't really respected me in our early past makes me doubt her.
Please Help me. Please tell me what do you think

She slept with you the first night you met, what kind of girl did you think she was?

She hasn't cheated on you so just let it go (if you didn't both say you were exclusive at three weeks, then you weren't).

23 people isn't all that much if she's sowing her wild oats in fits and phases, not with regularity.

She trusts you enough to tell you and you're together.

There's something deeper in that. Try not to overreact.

It was not cheating.