I (17 female) have a little cousin (7 female) who I am calling by her nickname, Mimi. So Mimi's mum is currently going through chemo and is in a really weak state so Mimi is living with me and my family. 2 important things to note are that my mum and Mimi's mum are identical twins and Mimi's dad died a year ago. Anyway, even though she does not understand the full situation, mimi knows that her mum is dying and because of this is very sensitive and clings to my mum since she reminds her of her own mum. About a week ago mimi had a play at her school which she was the lead in, she had been practicing for months to make her mum proud, now that her mum can't see it then she begged my mum to go watch it and record it so she could show her mum. My mother promised her she would come with me, mimi was thrilled and went straight to her room to practise lines, as soon as she was gone I saw my mum exhale and roll her eyes while she thought I wasn't looking. At the time I put it down to stress, until the performance day; I helped mimi all morning to get ready, do her hair and even a tiny bit of makeup(blush and clear lip gloss only) she felt like a princess twirling in her sparkling blue dress and it warmed my heart. As she was performing however, I watched her eyes search the crowd and she saw me but then noticed the empty seat beside me(my mum's) and I saw her smile drop if only for a few seconds but she seemed like she was about to cry. As she stepped out for her next scene I cheered louder than anyone else to show her how much I cared and made sure to record the entire thing. I put on a smile for her as we headed to the hospital so she could visit her mum with flowers and show her the video. After I left her to speak with her mum I saw my own, standing in the waiting room, tanned and smiling as if nothing had happened. As I realised what she had done, I saw red and blew up at her for how terrible she was that she broke her promise to mimi (who she knew was counting on her to come) so that she could get a spray tan and her hair done. After I was done she just scoffed and called me ungrateful then tried to walk over to mimi and her mum. I stopped her saying she had done enough damage and couldn't go in until mimi was done and out of the room. I could just imagine little mimi trying not to cry and instead just forgive her when I knew she didn't truly mean it. She rolled her eyes and went to sit down, I returned to the hospital room and spoke to the doctors, about 15 minutes later me and mimi went back to the waiting room and my mum was gone, me and mimi then went home as her mum was asleep and I haven't seen my mum since. She just texted me 'Your almost 18 so if you love your cousin so much take care of her yourself, I am staying at a friends house.' that was a few days ago, I haven't seen my mum since.