Help ! How to "dump" a girl without hurting her much ?

So last friday was a strange day.
Went to a school party that my old school does every year and met the nice 7/8 blonde girl I had been talking since last week. She's pretty, hot, same taste in music, seems like a dream, I just didnt feel any "flame" making me want to talk to her, but I thought, hell should be a dream.

Got there, saw her and started walking around with her, one hour later we're making out, but I just felt bored.. yup, bored, and I might say a bit disgusted. And I completely don't know why, like she's hot, I felt attracted (my lower head did) but my upper head just said, nope, I don't like this, I'm freaking bored dude, and we had tons of kissing with me basically suffering xd She didn't notice it, I got to run to my friends and didn't talk to her since then (I have exams so I have that excuse), she asked me for my number and today, she said she wanted to be with me (I went to school to have only one class and got back home without seeing her). I don't wanna hurt her but, not only am I not interested, but everytime since my last big crush ( a girl I've talked about here that basically screwed my head) when I think about relationships I feel almost claustrophobic.

So I'm in a pretty bad situation right now.. I need to "dump" her without hurting her (she's a really nice girl) and need to get myself fixed, is this normal, not enjoying making out ?

It's not like a LTR relationship.. we met a week ago, but anyway I feel bad :/
I will try NC in what I can, only message back, things like that, show her I have no interest I guess.

Thx for the help guys !

I dont agree at all with this thread.

I think you should tell her exactly how you feel. Tell her how you're not quite feeling it. - If you personally feel you could try to get to know her, then go ahead and tell her that you can see where it goes, but not to get too attached. Furthermore, I'd tell her how you feel about relationships due to your last crush.

Being honest is only fair because it is what we want of girls and I really think it is the best way to achieve what you both want in this situation. Also NC is a cowards way unless she be crazy.

I had decided myself to talk to her tomorrow anyway. I don't feel good by ignoring her totally.. gotta face the adversities. Thanks guys, hope she reacts in a "good" way.