Using that sort of power--in making other people sad, is a terrible way to live life. And it looks like you don't want to be that sort of person either. Positivity is something that cannot grow when your heart is full of pain. Give yourself time. And give the girl some space. You're lashing out and while it may feel good at the time it will always leave you guilt ridden and feeling terrible in the end. You need time to heal and being around that girl won't help at all.