Don't know how much this will help (I would probably be inconsolable right now), but I'm moved to say something because I know how this feels and I don't know if you have people close to you that will tell you this. I am also emboldened by my (assumed) anonymity.
Try to look past this. There's definitely an element of randomness in these decisions. In the sense that if you erased the minds of the adcoms and asked them to select again, the outcome would be different. This decision they've taken says nothing about your quality, as an individual and in relation to others, and it has no bearing on what you can (and will) achieve in the future.
You probably already know this, but sometimes it's nice and reassuring to hear it from someone else.
Now that the interviews are done, maybe we can benefit from some reflection while we wait for the final decision? I know I would. Turns out the QA wasn't really worth getting worked up about - I definitely overprepared (if that's a thing). Made a few unflattering mistakes on the first two questions though. Nerves, I guess. Hopefully it's not material.