Three areas in our lives which are most vulnerable to problems are our body; our group,community, or society; our family. These are also three areas which bring us much joy and purpose. These areas require continual effort to remain healthy and productive, and family should override the others.
There is a huge responsibility in raising, guiding and/or caring for family members. This obligation is yours, and should not be solely relegated to schools, institutions or other people. To do so might signal personal problems so common in our society. Yet to not do so might hurt a family member instead of helping him/her.
Do the best you can, and put all your effort into that family member. He/she needs you. If that is not enough, then look to outside help. It is the end result which is most important.