OP - The truth is, this girl didn't friendzone you... you friendzoned yourself with this confession of yours. Never EVER confess your feelings for someone outside of a relationship. It never works.
In the future you should just man up, ask the girl out on a proper date, and if things are going well make a move. If you make a move and the girl rejects you then you just forget about her, suck it up, and move on but chances are she won't since if she said yes to the date then she has some interest in you as well.
Any time spent being just friends with a woman is time wasted when you consider the fact that you could have used that time to find someone who actually wants to be with you. I swear so many guys now are afraid of offending someone or being rejected it is ridiculous.
Honestly, I don't think you should even bother meeting up with her on Monday. If she asks you why you should straight up tell her "look, I could see where this was going and I wanted to spare you and me the awkward conversation".