Muffy, don't blame yourself. Realize that no amount of preparation or defense training could have guaranteed his safety. You are a great Mom.

I agree that everyone should learn basic self defense measures. Choose those that you feel comfortable with...(carrying pepper spray with you does not good if you are afraid to use it.)

I was told the single most important thing to help insure your personal safety is

Always be consciously aware of your surroundings
Know where you are in relation to buildings, people, lights, streets. . .everything. Learn to do this instinctively. Waiting until you are faced with danger is too late.