How to straighten out my sister?

She is so disrepectful.She just got finished getting me in trouble for being nice to her. She has the smelliest attitude, and shes lazy!! She refuses to do any extra work, and when she HAS to do the extra work she runs to my mom with her crocodile tears complaining about reasons why she shouldnt have to and my mom SIDES with her feeling sorry for her, then has her make me do them for her making my life even MORE miserable!!! Theres no dad in the house so i already take on all of my dads responsibilities!! Plus the chores i take on as a result of her laziness!! Ive tried talking to my mom but she only says that by doing moree work that its going to make into a better man for the future. And shes been telling me that ever since my dad left!! like 5 years ago. IM so worn out physically and mentally from having to do all extra labor that a 15 year old shouldnt have to put up with!!! please help!!