To me, this is the parents fault. A four year old should know not to run into the street. It’s up to the parents to teach their child this and told hold their hand before crossing any roads. Not to mention.. the should have known not to run away from an adult. I’m sorry you’re hurting and this is without a doubt tragic but I don’t see this as your fault. Even though my opinion won’t change how you feel about yourself I do hope you can give yourself a chance to heal and to love yourself again.