Trapped In Own Home

I recently messed up and make fun of my 20 year old sisters nose, which she was really sensitive about. I only found out about her feelings after she cried to my dad, who favours her, and he flipped out on my mom. I only heard about it the next day from my mom and I had no idea it hurt her. I also found out that she went behind my back to other people telling them how she felt but continued to act as though nothing was wrong to my face. So now with all this my dad and sister are not talking to me and my mom is still there for me although she's still distant as to avoid being harassed by my dad. I just feel soo alone I want to get out for a couple of days but too scared that my dad will get upset and take it out, verbally, to my mom. I feel trapped in here and I don't know what to do. I use to be a cutter but stopped for a long time and I recently cut myself over this. I feel like I cannot talk to anyone about any of this. I'm mad at my sister for not coming to be about how she felt and going behind my back complaining and whining to other people and that those people (who are my family) didn't mention anything to me. I hate my dad, that will never change and too scared to open up to my mom in case my dad will retaliate against her.