I scared my friend--what can I do to make it right?

The other week me and my friend had a sleepover, we watched a gory/scary movie and she was totally grossed out and freaked out. I told her before that it was rated R and asked her if she was sensative to blood and she said no, but she still really got scared. I feel realllly bad about it now and I think she might be kinda upset about it. What can I do to make things right again? Was it my fault?