(((((((((Inny))))))))))
You are not weak! Just by packing a bag and making a solid plan to get out, you're showing a massive amount of strength. I am so sorry about what your husband did -- it was wrong and he had absolutely no excuse to do it, not because of anger or stress or exhaustion, and especially not because of anything you said or did. I agree with others that you should get out sooner rather than later. Getting your husband to get therapy or counselling is a good idea, but you should get him to do it after you leave, on the condition that you won't come back until he does. The fact that he would so lose control
with your child in his arms signals that he probably isn't going to think about his actions before he does them, and you can't risk yourself or especially the baby getting hurt the next time your husband lashes out.
Sending lots of hugs. I hope that you can both get the help and support you need to get through this difficult time.