How can i prove to someone who i am madly in love with that i will not hurt them?

all i can say is, don't cut yourself. that will hurt her as well. anyway, i sorta had the same thing happen to me, but as the girl, not you; and if you want good advise, just apologize to her about everything, act normal before you got into this love drama because that's the guy she fell in love with, so without a doubt she will fall for you again. I personally hate it when a guy completely changes because he feels foolish around me and I just want to slap him and tell him to go back to his old personality. hope this helps. =) i wish you the best of luck, it's hard to find someone you care about this much.