Really?? That's what your arguing with me about??

Well here goes.. I live with my bf and his parents. Well me and his 12 year old sister wear the same shoe size. She's been asking me for a long time if she could wear these shoes that I have. I finally said yes last night. Well I wake up this morning to her mother bitching at her because she doesn't need to wear my stuff... When IIII told her she could. I mean I atleast have that right, I thought. (She's actually still bitching at her right now and I'm getting more and more angry.) Well  shortly after she was bitching At her the first time here comes my bf bitching at me becuSe I need to tell her no she can't wear MY things. That she needs to ask her mom first. And I'm like for wearing shoes?? And he's like yes. And I'm like that's stupid. He said no it's not your gonna make my mom hate ou. And I'm just like whatever I'm not arguing about something so stupid. Oh and might I add that she just walked in and told me that she isn't aloud to ride the bus home this evening. Which she usually does if I'm home for her to be able to. Well I guess her mom said she isn't aloud! Now I guess I'm a bad person for letting her wear MY shoes. That's f&@king bullshit in my opinion. I don't know if I can take much more of his mothers bitching before I explode!!