I'm sorry.
Death is such a hard thing to deal with. I had 3 people that were extremely close to me die from cancer.... and it honesly felt like my whole family died. It's still very had without them here. I don't handle death very well, and I think about it far too often now. Cancer scares the hell out of me... I consantly fear it's going to take another person (or more) that I love.
If you don't mind me asking how old was your sister when she died?
I'm so sorry for your losses... for me I just try to surround myself with my family.. so if something ever does happen to them (or me) untimely I can say I spent a lot of wonderful moments with them. Also... try to think happy thoughts. Your life will become very depessing and sad if you let it consume your mind. It's very painful... but you have to try to go on with your life. ::hugs::