I Lied

I lied to a friend today. And it makes me feel horrible. I don't know why I did such thing. Maybe because I want to be complimented or something. Now I keep wishing I didn't said yes when she asked me. What am I gonna do? If I tell her the truth, she'd be disappointed but if I don't, she'll find out sooner or later. This is hard. I can't forget it no matter how hard I tried. Please. Help me.