Deterring a bad person is an important skill. I have been studying some of the best disciplines and persons that keep safe distances in combat situations. Kamaru Usman is a master at spacing his opponent. Watch video of him in UFC fights and you will see what I mean.
This judo video does a great job giving visuals on good distance between opponents.
I have concluded being effective in countering opposing strikes comes down to leg strength. A person must be able to crouch and lunge from a good distance. I suggest doing body weight lunges and squats to build the necessary leg strength. It is free and effectual exercise. (Obviously, consult professionals before attempting something new.)
To work on safe distances, stand near a wall or pole and put your arm out. Visualize a longer arm and a shorter arm. Gauge what you see.
Spacing and leg strength are two things that can keep you safe defending yourself and your family.
Application for fathers: do these exercises with your kids. Have some fun with them.