Why does my mom keep forcing me to include my 6 year old sister?

I'm 13 and my mom keeps making me play with my super bratty and annoying 6 year old sister. I have a PlayStation 3 and I got Minecraft fory birthday. Anytime I try to play, my mom FORCES me to let my sister play. And my sister, in the game, breaks everything and messes it all up! I will spend hours building something and she will come along and break it! I try to explain this to my mom, but she says it's not fair that I get to play and my sister doesn't and she says that either I have to let my sister play, or I can't play. It's not fair because it's MY game and my sister has ADHD and she ruins everything. I miss so badly being an only child and being able to play things by myself and not have a stupid child yelling at me. I hate playing with her and it makes me so mad that my mom can just force me to let her play! I need help.

So get another game you don't like very much. Have it ready to install when your sister wants to play with you. Let her do what she wants with the other game and save your Minecraft for when she gets tired of playing and leaves your room. I know its a lot of work, but that way she won't mess up what you've created.

So you will learn kindness, patience and tolerance.
VERY IMPORTANT skills to learn IF you are going to be happy as an adult.

Nnaybe you can teach your sister not to break your stuff

Make two separate worlds on your game. Have one be specifically for you and the other for you and sister. That way if you want to build something and not have it destroyed it'll be kept safe on another world. Siblings are supposed to be annoying anyways.