How do i forget them

I have a problem. I have a total crush on a girl. At first she wrote to me very often, complimented me, etc. Then we had no contact at all during the Corona period. Finally she wrote to me again in August and wanted to have sex with me. And whenever I pay attention to her, she looks dislike and somehow feels like "I don't care" that totally annoys me. First she writes me I should come to her and watch Netflix and then after 1-2 months if I suddenly give her attention she is completely different and I don't care. Whenever we have no contact within a period of a few months, she suddenly writes me again. It really annoys me and I just want to forget it, but it's extremely difficult for me. I see her at school every day and that makes it harder to forget. Do you have any advice?

You have gained nothing from her. Forget them, delete their contact. She needs you when she got a rejection from another boyy or something. I wouldn't want to tolerate such unnecessary behavior

Do not meet her again if she ignores you

didn't you ask her why she is like this?

It may be that she does not want to admit that she has feelings for you and is therefore repellent and wants to forget you. But then she realizes that she misses you and wants to see you. I'm a girl too and that's the way it is with me right now I'm not exactly sure if I have feelings for my best friend and I also have some emotional chaos like the girl you told us about. Maybe it is.