I need help my family is stressing me out?

i'm 21 and live with my mom and big bro. my mom is a singel parent and me and her are the only ones with jobs idk what to do. my bro is 22 and never had a job and he is always playing world of war craft everytime we tell him to get a job he walks away. i know he is angry and depress tho that isn't an exscuse to not help your family out. i don't want to lose my house just because my bro isn't helping. i told my mom he need to see someone but i know him, he won't talk. the one thing that scares me the most is what if he tells my mom about me and my gf. my family don't know i'm a only my bro and some friends. my gma the other day told me that i have to now be the big sister tho that just makes me even more stress bc i really feel that it's not my job to take care of my brother. it just hurts me alot and some time i just feel like i have to give up the only thing that makes me happy (my loving gf) to make my family happy. i want to run but i can't leave my family. help me plz!!