Hi S.,
Unfortunately, this is a lesson our girls have to learn even at this early age.....I had a 2 similar situations with my daughter. It was a hurtful experience, but I spoke to her from the heart and explained how catty girls can be and why things happen the way they do(I spoke in words & terms she could understand). Luckily, my daughter understood my explanation. Try explaining that sometimes different personalities don't always fit together or work well together. Perhaps setting up play dates with other little girls so that she sees that there are other possible friendships. If possible, set up a play date with someone else everyday for a week so that your daughter won't depend so much on "K" in after school. Tell her that if "K" makes her cry then perhaps she is not a true friend. True friends stick together...etc. I found it truly amazing that at the tender age of 7 and 11, I had to explain how catty we women are and why and that sometimes we are better off without someone as a friend. Speak to her realisticly, from the heart and on her level. Good luck.