Hello Abi!
You sound like such a nice person!
Anyone who'd even think of being mean to you is just not worth being around or paying attention to. I know that ignoring a bully is easier said than done, but when you show this girl that you won't even
listen to her nonsense, she hopefully will realize that you really are a strong person and you don't care what others say about you. Don't show any kind of reaction, because that is what she is looking for and you can't let her think that she has "won." Ignore it, and soon enough, she'll realize that being mean and spreading lies about you is a waste of her time.
Also... (and this is really, really important) keep on being the nice, kind person that you are! Do random acts of kindness, especially towards the people this bully could be spreading rumors to. They'll see firsthand how kind you really are and won't believe anyone who dares to say that you're annoying or mean.
The peculiar thing about bullying is that, no matter how hard bullies try to make you feel inferior to them, you will always be better than them because you know and understand the importance of respect for others.
I really hope this helps, and I hope this gets better for you soon!