Your feelings are normal.
Your daughter is a top student, she invested a lot of time and energy in HS, you have the money for a more prestigious school, you identify as the parent of a top student…and she chose a “regular” school.
It’s going to be hard at first. Four months from now when you tell people she goes to Auburn, you are going to be tempted to add that she turned down Vanderbilt. Adding that last piece of info will make her/your identity continue.
A year from now I have a hunch you will be saying…she goes to Auburn, and she’s doing this, presenting that, traveling here, has a great research position etc. It takes time to grieve what you thought might happen.
Suddenly her school won’t matter …because her accomplishments will define her, not the school.
As stated above, cream always rises to the top.