Here's My Heart Wrenching Story of the Day

Today L was going to her friend C's b'day party. Before we left L had mentioned something about C being her "best friend". I don't really care for that term just because it seems like someone's feelings are bound to get hurt. Can't you just picture a bunch of preschoolers out at recess and a whole conversation about who is "best friends" and who isn't? So I said to L " you know you can have more than one best friend." She said " I don't want more than one."
Fast forward to the party. It was a small party, only 4 little girls and L is very comfortable at C's house and with C's mom so I dropped her off instead of staying. I came back to pick her up about 20 minutes early just to make sure she was okay because I've never left her at a party before. She looked really glum when I arrived and ignored me. I finally got her to give me a quiet sad little "hi mom". Then A's mom arrived to pick her up and A said "mommy look what C gave me." It was a necklace with a plastic charm that said "Very Best Friend" and the charm was half a heart and C had a necklace with the other half. You know, they fit together to make a complete heart. So C, the b'day girl, had given this to A at the party right in front of L, clearly stating that L was NOT her best friend. As I stood there trying to control my impulse to strangle both C and A my little L asked very sweetly of them both " Can I see your necklaces?" They both snottily replied " NO!".
When we got home and I was telling this to Hubby I almost couldn't hold back the tears. I know I'm hormonal and all, but how the hell am I ,as a soon to be mom of three girls, to deal with the mean girl crap of adolescence when I can't even handle the unkindness of four year olds?
Both C and A are in L's preschool class so you just KNOW they are going to wear those stupid god damn necklaces to school and make L feel sad all over again. Now I know these two little girls aren't mean and intentionally trying to be hurtful. They're only four years old. It just sucks when you can't make everything all peachy for your kid.
At bedtime tonight I brought this up with L again. She was in a happy mood so I really considered NOT saying anything about it again but I didn't want her to have any confusing feelings about it. I asked her how she felt about the necklace and she said it hurt her feelings. I told her I didn't think that C and A meant to hurt her feelings and if they or any of her friends does or says something that hurts her feelings she should tell them that because maybe they don't realize they are doing it. She seemed fine about it tonight but I still have an ache in my heart. I'm pathetic.