Just read this Ruby and felt so glad of the wise advice and loving support here for you, much needed. Can't blame you for feeling so bitter and angry at all. I too know the pain of having a child with depression and all that entails. Your family sound a cowardly and selfish lot, but it's possible that they do care and simply do not know how to show it, obvious though that would be to you. I would avoid making irrevocable decisions whilst in the grip of pain, grief for your lovely dad, angrer and emotion-mind, but wait patiently and bide your time for a period when you feel a bit more grounded and calm, to reassess how you feel about them and what you want to do. I'd also agree with those who suggested some counselling - I've found that Relate is excellent and not simply for marriages/partnerships but help with other family or friend relationships also. At the least it will allow you to voice your feelings and could help you focus more clearly.
For now, simply ask yourself what action would best help you feel proud of your responses right now, when you look back at it? And which would you feel hadn't helped the situation?
I hope that the funeral went as smoothly and well as it could do, and that you gain some comfort in the days and weeks to come.