Anger issues

I need help I have a 3 month old baby and serious anger issues. I feel really really bad for being mean to my baby and every time I promise myself I Wil stop I will do better. But before I blink I have lashed out again at one of his crying fits. I am afraid that one day I am going to lash out and really hurt him. I don't want to. I am trying to redirect my anger towards exercising but I only just started. Can someone tell me if it's just me and how on planet earth do I deal with it???????