Why does my dad hate me so much?

When I was 9 my grandad died and my brother was born and that's when my dad got really depressed and started to hate me and I understand that because he just lost his dad and my brother wasn't planned so I know and I was a weird kid, I said things that I shouldn't have said and I was being bullied allot in school and I didn't have many friends so I kind of going through my own stuff and I was going into the awkward stage too and I know I said and did really stupid things and I regret it so much because my dad hates me but at the time I didn't understand I don't know why I said the things I did but I remember at the time I believed everything I said and I don't know why? hed do and say really nasty things to me like hed tell me I was the scum of the earth and that I was nothing and he was just always really angry and short with me. I didn't know what I was doing to make him hate me so much and after hed do or say something horrible he'd hand me some money I suppose to try make up for it but hed still never talk to me and I didn't know why? I didn't understand what was wrong with me? so I stopped trying when I was about 13 and I stopped talking to him and for awhile he was grand with me when I was a teenager, and he'd talk to me and stuff but now im in my twenties and hes just gone horrible again and I don't know why? I don't know what I did? I never ask him for anything, I don't talk to him unless I have to but he just shouts at me and is really horrible and I don't know why?. Hes always been great with my younger brother and although him and my older brother have had there ups and down they generally get on ok, there not very close but my dad isnt horrible and angry with him all the the time like he is with me. I cant talk to him about it its really and truly not an option so please dont suggest it, Could anyone give me any suggestions on why he might hate me so much? Iv been trying to figure it out since I was 9 years of age and I really dont know why? so an outsiders view would be great. Thanks =)