I really hate myself and I can't bare feeling like this?

It sounds weird but a few minutes ago I just realised how much I hate myself, I'm so pathetic and needy and just hurt everyone around me and tell myself I'm right when I've done and said some really nasty things to people recently, I'm immature and I literaly feel sick when I look in the mirror and think about the kind of person I am, I hope it's just some kind of temporary thing but if it's just me seeing myself for what I really am then I can't bare it, I know that sounds weird, can someone give me advice please I've never felt so crap in my life.. if it is some kinda wake up call then I want to change.