The past is the past

You can’t change that
So she has more experience
Learn from your experience
Live for today

So what if she had other people before???

Obviously, things didn't work out well with them or they wouldn't be her exes, would they???

You do need to establish some healthy boundaries with this friend though. Simply tell her that you don't care to hear anything about your girlfriend's past relationships because it's in the past and no longer relevant to her relationship with you.

Well, no need to hurry to make things perfect first time.