I hit my pregnant gf and i feel horrible but i didn't know what else to do...?

My gf just came home from the hospital yesterday =/ after she was hit by a drunk driver and i almost lost her. Well i have been taking care of her since she is on bed rest and everything we are both 24 and well she is 4 months pregnant with our first child and everything. This morning she was asleep and i had to wake her up to give her her meds the doctor put her on to help with pain and healing and such. And she like freaked out and started chocking me i don't understand it and it scared me shitless i didn't want to hit her i kept shaking her and screaming but i got to the point where i couldn't breath so i punched her in the face =/. I feel so horrible about it but i didn't know what else to do. So i left and just went for a drive and i was crying so bad i couldn't see so i stopped and called my big sister and explained everything and she doesn't seem to think its that big of a deal but i do. I mean i hit my gf and i feel horrible for it. What can i do to make it up to my gf? Advice?