How hard it would be to explain rape to a 7 year old. The good news is that even though your child heard some things and has some probably disturbing questions, the thoughts that he/she is thinking probably aren't anything like the thoughts those words bring to mind for you. Kids this young have limited understanding, and that is a blessing!
So, try not to panic, don't let your child see that you are disturbed, and feel free to answer some questions with a simple, "You know, we will talk about that when you're a bit older, because it's hard to understand right now and you just don't need to know it yet." Don't feel like you have to answer every question in detail. Obviously you'll need to answer some of their questions, especially things that they seem really concerned about, but it's not going to hurt for you to just tell them not to worry about subjects that they just aren't ready yet to hear about. Your child will likely forget all about it very shortly, and you can bring up the subject more at a later time in your own way.