Amy,
The loss of a parent is very difficult---no matter how old you are. It sounds like you not only lost a parent to cancer but one to grief. I think it was very wise of you to seek support here from those who understand the pain of your loss. I would also hope that you have the support of others in your community. Many communities have grief groups through local cancer support centers. I've worked with several in our area who hold groups, work with families or simply share ideas about how to cope with grief and loss. They may be a source of inspiration to get you through this week and help those you love. Some centers may offer counseling directly or they may be able to refer your family members for a treatment evaluation to determine whether medication would be useful.
Take care