My best friend (F17) of 4 years likes me (M19) and another dude, we also both like her but I was too slow, to clarify the events of what happens is she’s waiting till 18 to make anything official

So we both like her and she likes both of us however he told her that he likes her first.
I’m handling things as best as I can, and all I can really say is that, I’m kicking myself and we’ve openly spoken about how we feel about this.
She doesn’t want to cur him off as she hates thinking the she led him on, and she said she wished she waited for me as she liked me for a long time. She also says that if he leaves then she definitely wants to go out with ne

I completely respect the situation and her choice that she wants to try with him as they have already expressed interest in each other.

I’m just not entirely sure how to handle the situation in myself and idk what to do, I know this isn’t strictly relationship stuff as much but I really need some help as to what to do.