The first step is that you should talk to a professional who can get you started in the right path of getting better. Getting help from a counselor is very important and can provide you much help and insights in dealing with your current problem.
In addition, here are some techniques a parent can use to help manage their fears and depression.
Learn to manage your depression and taking care of the kids at the same time. Parenting is a 24 hour job and so is taking care of your mental health. If you become overwhelmed ask your spouse or other family members for help. Learn to share the responsibilities in the household. Communication with the other members of your family is very important.
Learn to manage your negative thinking. Instead of focusing on your anxious thoughts try to think of something positive. Read a short book or read some affirmations that will make you feel better. Remember not to dwell on your depressing and fearful thoughts.
Be able to organize your daily activities so you do not become overwhelmed. Set some time to reduce your anxiety and stress when your not taking care of the kids. If the kids are at school, take a walk or do something enjoyable that will make you happy and relaxed.
It is not easy to deal with your depression and fears. Once you get some help from a professional, things should become easier. Remember that there is hope for you and there are ways to deal with your fears as a parent. Just be patient and not give up.