I asked my female classmate for the WeChat ID of the girl I like, but at first she refused to give it to me. Then after I pestered her for a few days, she finally sent me a WeChat ID?

It is impossible for her to give it to you, because she always thought that the person you liked was herself, and she also liked you, but she didn’t expect that you would ask her for the WeChat ID of another girl, so She was very sad and disappointed. So you should comfort her, make it clear that you already have someone else in your heart, and say sorry to her. As for the WeChat account of the girl you like, just ask her directly for it.