Women help Made a Mistake!?

I told this girl i like her and shes liked me for a long time but like usually im having serious second thoughts on the whole thing she lives 2-3 hours away from me and she use to go to my school how can i tell her that i dont like her. I haven't felt this bad in a LONG time for telling her i like her when i really don't.. I think I like her because in the winter time i start to get a little depressed and run down and Christmas is approaching so i just don't know!

Separate Question about depression should i be exercising regularly cause I've stopped (yet again winter time has made me un motivational) and ive put on some weight it feels like 5-10 pounds but looks like 20! i feel just awful and it only happens from December to February