Asked a classmate out

Recently, i asked out one of my pretty college classmates during a quiet moment after class the other day. This was after spending 3-4 days talking to her and really trying to get to know her and she was being really talkative and we seemed like we were having great conversations. At the same time, a friend of mine was helping me work up the courage to ask her out by giving me advice and telling me not to worry about if she says no. So I finally asked her out, and I ended take the answer that she gave me as a yes. I said to her “how would you feel about me taking you to dinner sometime?” And then she told me “sure, but where would we go?” In my mind, that was a yes. After it happened, I was so excited and I immediately went and found my friend and told them that she said yes. Her and I traded Snapchat’s and I sent her a message straight away, but she never opened it. The next day, I sent her a snap of my face and then after 4 hours, she still hadn’t opened. So then another 2 hours later, I asked her how her day had been going and then another hour passed by and I noticed that at some point during that last hour she had opened up my three messages and she ignored them. And then from that point on, she’s been avoiding me. And now I’m just the most confused that I think I’ve ever been in my whole life. At this point, it’s obvious to me that she didn’t really want to go out with me, but why didn’t she just say no when I asked her? Why did she lead me on and crush me like that? And this is one of only two times that I’ve ever asked a girl out in person and at least the other girl actually told me no instead of playing games with me. And now my confidence has become completely crushed and I’m so scared to ask another girl out now. I just need some advice on how to get my confidence back.