OK so I guess I'm not important

I have a problem and no amount of binging through bl and yaoi is getting me over it

Deep breath

So I am having a birthday party and all my friends canceled on me
My mom was soo excited and she prepared a lot for it and stuff cz it's my first birthday party ever (my sister holds a party for hers every year but never me so, she even invites my friends and they show up to hers) and I'm turning 18 which is very important year here so she wants to make it special

How do I tell my mom that ya I'm vibing by myself and put of like 20 people almost no one is coming
And out of all those people I invited, the ones to refuse immediately where my friends, yes by iimportant friends I mean the 5 people I hang out with all the time and spend my high-school days with. Without saying reason they were like I can't make it I'm busy,,,, -_-
It's my most important birthday too I'm turning 18 so I'm a legal adult now,,,
Sigh I realized I attack too much value to people like I make sure to be there for everyone and on one day I want someone to be there for me,, Noone even want to like OK bro I get it

Now how do I tell mother that I guess your daughter isn't important enough so don't prepare anything,, ya already ordered the tow tier costume cake too ,,,,

Right now I am feeling like crap and thisclose to jumping over a cliff