What happens if you accidently hit a pedestrian at a corsswalk at night but it was a green light for you.?

it was around 11 oclock. i was driving around 40mph on the streets the light was clearly green. all of a sudden i see this old lady with a cart and i tried my best to stop but i hit her accidently. she was at the crosswalk. she is sueing me. how bad will it be. at the crosswalk the red hand tells you not to walk. she claims that she was already in the crosswalk so she gets the right of way but my light was green and it was late at night. i did by best and i feel terrible but what will happen?