That mean girl who takes everything away

I like a guy and we start to date
with a beautiful relationship we began to create.
Then she came along and stole his heart
introducing them really wasn't smart
I began to like her old boyfriend
I thought they were done, fineto the end

but then out of nowhere they were back together
it seemed like I'd be alone forever and ever

I lay in my bed and start to cry
because my best friend was the one who stole my guy.