After all, she did not know.

What she had seen had seemed bad enough and strange enough, but apart from the fact that Beatrice had been found upon the altar, where she certainly had no business to be, and that Unorna had acted like a guilty woman, there was little to lay hold of in the way of fact.
"My child," she said at last, "until we know more of the truth, and have better advice than we can give each other, let us not speak of it to any one of the sisters.

In the morning I will tell all I have seen in confession, and then I shall get advice.

Perhaps you should do the same.
I know nothing of what happened before you left your room.

Perhaps you have something to reproach yourself with.