BIG problem with my parents. help!?

Ok so my parents got divorced about 3 years ago and now I live with my mom and my stepdad. I really don't like my stepdad because he drinks a lot. Everynight at dinner he'll be drinking wine, and some beforehand and maybe even afterwards. Some nights he leaves dinner early to collapse on the couch or after dinner he'll go straight upstairs to bed, falling down the stairs on the way. When he's drunk he also has a really short temper so he picks fights VERY easily with my mom at night, if she says one thing out of order he'll go crazy and start fussing at her. It pisses me off so much. Tonight i went downstairs to get some water and he straight up said "Your impossible." I didnt do anything or say anything to him and he feels like he has the right to do that? I don't know if my mom is even happy with him anymore of if she feels as if shes trapped. If she is happy, I don't see how. I'm pretty sure by now my stepdad is an alcoholic and its doing a lot of damage. I've been hurt so many times because he has been drunk. Not physically but emotionally, and I can't take it anymore. Tonight I was extremely close to running away. I can't bear living here anymore, knowing he's like that. My mom is so happy and cheerful until he comes along with his drunk self. I don't know what I should do. Talk to my counselor about it, tell my real dad, please help me and give me some suggestions. I can't live like this anymore. Tonight I broke down crying because I think I've finally cracked.