My friend is WAY to clingy to me.?

She always askes me to come to her house to her house for a sleepover. I go everyweek. At Lunch, Me and Daphne (my OTHER friend) Were planning a sleepover without my friend. Laurel (The clingy one) Got mad and was asking if she can join us. I just shrugged. I dint want to hurt her feelings. Laurel invited me to a retarded tea party with a fudgin' five year old.. :l I said No because i personally think that little girl is a BRAT. I have a scar from her throwing a rock at me. Laurel always sits next to me and budges into me when i am talking to my friends. I asked Laurel to stop alot. She said she feels "Left Out" But how do you I feel when you tell me "Oh my Best Friend is coming!" When i'm right there. I cry alot because she ditched me plenty of times for the little girl. Should i End our realtionship?