Why do lash out andyell and get angry with our family members sometimes?

So here what happen my grandmother told me that i going have to start eating down staris. But i have a table in my room that i eat on and i don't make a mess and i always clean up my room. I told her that i can eat in my room if i want im 18 years old i pay the whole rent in the townhouse apartment we both live in. Then i was yelling at her from down stairs and i was slamming my room door 3 times because she was running her mouth. My mother live with us now and she came in my room and told me i too say sorry to my grandmother, but i told her iam sorry from up stairs and i did not tell her sorry in her face. She buy 6 packs of beer every single day and she probably was drinking when she was telling me to eat downstairs. she always say stuff to me just to mess with me sometimes when she drinks. i have a big black table in my room that i eat on and i don't make a mess. and i have a cable TV in my room. can i just have peace to my self sometimes. iam a good boy who don't cause trouble , dont smoke, don't take drugs or don't mess with nobody. The reason i bought the townhouse apartment for me and my grandmother so that i can have my own room. Im 18 years old and i pay the whole dam rent in the apartment. My grandmother only works if someone calls her to go to work. if she do works she get payed 400 dollars and the rent cost 650. And i get a social security check for 600 hundred something and i pay the whole rent, so how can she tell me to eat downstairs. i Told her i am 18 years-old and stuff.I call my uncle who recently had i car accident one month age and i told him what happen at my grandmother and he told me to control my anger and stuff ,because my uncle is bi polar. he told don't get angry and told to learn how to let the anger in. so iam staying in my room all day right now. My uncle told i can live him but i not sure about that becuase he is a control freak person and always tell people what to do. i think my grandmother and my uncle have probelm. so i am living with a alcholic grandmother and i have a uncle who is living with a woman and her three kids and him have bi polar . i have a soical security check and my mother is getting her soical security check soon? so should i live with my uncle or my grandmother because they both have problems sometimes? or should me and my unstable mother have live in together by our self? what can i do? and my uncle told me that i should be happy.