Feels guilty after my family was destroyed 11 years ago need help?

when i was little my mom use to abuse herself into taking drugs and my dad use to go out and deal drugs around the town. someone phoned the social services and reported them as bad parents. I use to have to clean my sisters nappies and make food for us. I was only 7 at the time and my sister was 2. I was scared and had no idea on what to do the whole house was a mess and a health and safety hazard nothing was clean. people use to come knocking on our house shouting for my dad because my dad owe them money and people use to shout through the letterbox at early hours in the morning.I never had any friends when i was younger nor did me sister, my mum and dad use to shout at me for being there. they use to have sex infront of me and my sister and preform sexual acts on each other. I have been told a lot of information about my mom and dad as now i am 18 and allowed to know. i was taken from them at the age of 8/9 and placed into care. i never attended school before i was placed into care i never left the house my parents didn't care about me and my sister. the house was all smelly and unfit to live in. but for some reason i find it hard to live my life without feeling guilt and i feel destroyed why my parents couldn't be good enough people to stand up to the responsibly and be parents. Me and my sister was placed on the high risk register from birth as my dad had been in prison for Violet crime i was also bullied at school for being the one without any parents this use to make me feel upset and angry. i tried to commit suicides at the age of 13 because of all the bullies. i have behaviour learning difficulties i missed out learning everything all children do from birth to 8 years of age. I was 8 and didn't know how to write my name!! overall i find it hard to live my life without having everything circulating around in my head. i always feel down