It took a long time...a very long time and much suffering...but...
MY MUM FINALLY APOLOGIZED!!!!
After I moved out, she started coming home to find barely anything clean and tidy and when she asked my sister to tidy up her bedroom she burst into tears and screamed that she couldn't [Quote - "I DON'T KNOW HOW! AMY USED TO DO IT!"]. So, whilst in the car yesterday, she apologized for always blaming me for the mess and for not appreciating what I actually did do. She also had a loud "discussion" with her boyfriend and my sister.