Kk so there's this guy that I really really liked at the beginning of this year. But soon I found out he was flirty with everyone. But I continued to like him. After a while he told me he liked me at the beginning of the year. Behind my back he told one of my friends I was immature and nit ready for something serious which kind of upset me. I soon realized the new girl he liked was like the same person as me, we honestly have the same personality. Only difference is, she is way prettier than me. And we are at the same level of maturity so.

Anyway I got over him or at leasty I thought I did. But last night there was a dance and he was slow dancing with her the whole night. It made me feel bad, I'm mean up until then I didn't care. And when he came over to dance with me for like two second when she had to go to the bathroom or he couldn't find her or something, it made me feel even worse

I neeeeed advice now.

What is it you need advice about. You got over him once, do it again. You are just feeling this way because you saw the two of them together and it brought back feelings.
There is something about this girl he likes so you two are not exactly alike. Get over it.