I feel for you, Didie - my sincere condolences.
I can only echo what others have said - take good care of yourself, get some me-time, and remember you are the most important person in other people's lives. People care about you.
You are going to be stressed for a while yet - bereavement is one of the highest-stress things going, and I guess you're also going to have the stress of sorting out your mum's house - and your older sister! Try not to let it get to you. Try to eat only what you know you can eat, get your exercise, and don't worry too much about testing. Have you a good friend you can talk to? I don't mean counselling, just someone who will listen while you pour it all out. It helps!
Big hugs from me!
Viv 8)