I am not trying to make light of this, by any means. But, you only hit her with a milk jug and it wasn't on purpose. It didn't hurt her that badly, probably more shocked over it than anything. It's not like you hit her over the head with a frying pan!
I cut my poor 3 month old daughter with the nail clippers the other day while she was sleeping. Woke. Up. Screaming. She was bleeding all over the place......it was terrible. You'd barely know it now, it healed very quickly.
I guess my point is that being human, we are going to do way worse to our kids to traumatize them through their lives so we can't sweat the small stuff that they can actually heal from. And I say that to myself too! I am certain that when my daughter gets out of baby phase, she's going to end up in therapy from all my mistakes!