I would also suggest individual therapy for yourself. Even if he did mention his father to anger you, you cannot respond with unreasonable force and anger. You need to let the resentment of his father not fall on your son.

Secondly, you son ran to your mother. You need to seriously think about why this angered you so much. If my son ran to Grandma, I would just ask Grandma to walk is both to the car. It was a completely over the top reaction to be mad he went to a trusted adult in his life.

Then, realize that you spanked your son out of anger and he hit you out of anger. They're the same thing. He hits you in anger because that's the behavior your modelling. Your teaching him that's how to do it.

Having said all that, I do understand the overreaction and fear when your child doesn't listen and just runs off. My 4 yo most likely has ADHD and he just does not listen. He is so impulsive that he will run off into the road, run away and he struggles to follow instructions. It is maddening and so scary as a parent. And it has caused me to be, at times overprotective. But that is also why you need to speak to your own therapist to find ways to address him running away from you in a calm manner that will eventually teach him to follow safety precautions. Instilling fear is not the tool to produce a healthy, well-adjusted adult. It's giving them love, confidence and tools to live in the real world.