I feel horrible...

It wasn’t your fault the other party bailed out on you the last minute. It wasn’t intended to be a date. One person has to ask the other person out and it should be a casual friendship. I would get a second opinion from your mother. If you weren’t doing anything romantic to break the church rules you should be fine. I’m LDS too, and 23 years old at that. If you and this guy are supposed to be friends, I wouldn’t call that breaking church rules. I’m sure your mother isn’t going to scold you for being alone with him. Don’t feel guilty about it, it wasn’t your fault this had to happen. I’m sure it was a mistake. And in order for someone to ask you out, you have to make the choice to reject the offer, or agree. But, since this was supposed to be a group of you hanging out at the mall, that’s botched. I’m sure it felt scary to be alone with this guy and I wouldn’t blame you for that. If you didn’t break the Law of Chastity, you’re fine. I don’t know what to tell you about stopping the rumors in school, but, you could go to the office if things get out of hand. That might get people to stop. Speak with your mother and your Bishop about it to get their opinions. But, in my opinion coming from another LDS sister, I’d say it’s not your fault and you didn’t break the rules of the church. Good luck and hope this can be squared away.