((((((((((hugs))))))))))) sweetie, you have a lot to deal with for one so young yet you are a great, thoughtful, caring and inteligent writer, fancy cars and posh houses are often the reason so many families have difficulties, because people try to have more than they can afford or give up on pleasurable things like spending time together. you seem very sensible, aim for quality time with your family rather than worrying about what others have. poor people are often much richer in feeling loved /supported by their family than those who spend every waking hour at work to pay for a great big fancy house and car they only have time to drive at weekends!
a new school will open up new opportunities for you to make new friends, maybe you will find some who are in a similar financial situation to your family, may be not, who knows.
give your grandparents and aunts a chance to spoil you, that is their job!you are certainly not a charity case just because they treat you to things, most extended families do the same regardless of wealth or illness in the family. they will only offer to treat you if they really want to, if they did not want to they wouldn't offer! they are probably very proud of how you are hanling the siuation with your mum and want to say thankyou for sticking by her and not making her life more difficult.
when you feel like hurting yourself, please set an alarm clock or timer for 1 hour, tell yourself you will wait till it goes off before you decide weather you really think it is a good idea to act on the feeling, in the mean time do something, anything to distract yourself from the feelings, watch tv, go for a run, play loud music and sing your heart out to it, talk to someone about the weather, any distraction should work, they are a great way of diverting/dispersing your feelings.
let your new school nurse or councillor know of the situation you are dealing with as soon as you can, she may have some ideas or suggestions that will help you .
most of all please keep posting on this site, you can rant as much as you wish on here, and you will usually get great feed back too!
Take care
Ted x