So my step dad is married to a girl .and she has 2 kids a 9 year old and a 6 and im 13?

her names susie ( my step mom) and jeff my step dad has been with me sence i was 9 months old ..and only been with susies kids for 2 years ..and they call him dad and it hurts me and susies girl the 9 year old dose it on porpuse to hurt me and every time i do something susie gets made at me and i feel like the 3rd weel.always! and it hurts me so much for me to hear my 3 kids out of my dad jeff ..cause im a only child and im use to hearing my kid not kids..but when susie says i shes says my step kid.:( and i have a mom but shes a drunk all the time and my father (real) left me when i was born..and i asked jeff if he loves me more than susies kids and he said i love yall equaly ..and it hurt me ! then susie always buys them stuff when im there and not me anything .not that i care but when i get something they have to when im with jeff...and i feel like my heart it tarring into little pieces ..and it wont stop !then the 9 year old said hes my dad cause ur mom wasent marride with him my mom is ..and it broke me up ..ya she got in troble just not in big ..and its hard to understand and when i cry about my mom being drunk all the time to jeff ..susie always says i should get hit with the baddle cause her kids do when they act like 2 year olds :( and my dad is with them every day and i have to switch with my mom and him ..is it true that i need to change..?? susie makes me sleep in the office on a couch ..and wont let me get a bed and they are marride !and when i told my dad i wanted a dvd player she said to her kids 1 first ..!! and its like i was the 3rd weel like allways! all i have is my friends ..should i change my acts what can i do for it to all stop ??? :( plzz comment