Yup. Say nothing. Take no further action. It is always semed to me that these sort of things tend to continue to build on the last thing. In other words, if you say something else (at this point), it's just going to sound wrong to her. Let it go.

In situations like this, I have always tried to remember the words of Evelyn Waugh who said "Never apologize and never explain. Your friends don't need it and your enemies won't believe you anyway..."

If she's your friend, then she'll be back. If not, what have you lost? Not much.