My mum has cancer and we are all trying to be helpful, of course. My issue is that my sister is driving me crazy. She is getting married in the summer and alot of the wedding (eg country venue) has been changed because of my mum, and this has made my mum feel guilty, so she is constantly teling me i have to be nice to my sister because its been really hard on her. in addition, my sister is constantly moody to me and then nice to my mum and when I am moody because of how rude my sister has been to me it stresses my mum out and i start feeling guilty. i know this all sounds stupid but its making me cry every second and putting me in the worst mood ever. another example is how my sister will make my mum all her meals, and finds out all these special dietary things, whilst im failing at making porridge and making the rice too salty, so much so that my mum tells me she doesnt want anything when i offer her, only to accept the offer from my sister five seconds later. I know this all sounds stupid and that what im feeling is just jealousy but its making me feel really really depressed and useless and angry, as if my help is so unneeded and im just burdening the family more. I want to tell my mum how i am feeling but i know it will stress her out