I think, if she’s a good friend and mature enough to handle it, you could tell her. There’s no way that that should come in between your friendship or make things awkward. You should just be clear on what your motive is behind telling her. If it is just to release it and sort of vent it out, then, by all means, go for it. I’m sure she’d appreciate it too. If she doesn’t, then too bad, because there’s nothing wrong if you’re not expecting anything from her and just letting her know as your best friend.

I think she is your friend and she will understand your feelings. I feel friends have their own maturity amd understanding between,so you can trust your friend and make her understand.

Yes, i think you can tell her. She is your best friend and both of you have shared a good bond till now. It’s your last day of school and now you can express your feelings with her. I hope she will understand being a friend. You don’t need to worry about that thing.
Have a happy last day of school and make it memorable.