dear Tup, I hope that you will accept my most sincere condolences for the loss of your dear mum.
It has to be a difficult decision whether or not your mum wanted you to worry through her illness and to see you being upset and crying, knowing that nothing could be done to help her.
I'm on both sides of this decision as I had to see my Mum suffer from being in a nursing home and there was nothing that could be done to help her, but then I have thought that if I have a serious illness whether or not to tell my two sons, of course they would be disappointed if I didn't, just as I would be if my twin brother became ill and he didn't tell me.
Please I do understand what you are saying and I feel so sorry for you, because it's a part of your life that you have missed out on, being able to talk to your mum about certain occassions that the both of you found the funny side to, and also those sad times when you both comforted each other, so I would be really disappointed like you if my twin was ill, and annoyed, and my two sons would also be frustrated with me if I didn't tell them because they both love me so much, just as you loved your dear mum.
Having no help from your sisters only complicates the situation, and to help your dad move house would also be devastating and a shock for him, as he would have known what condition your mum was in, so perhaps you may get some answers from him, if it's the appropriate time.
I wish you all the best. Geoff. x