I made a girl cry what should I do ?

My friends little sister has a crush on me she’s mad at me that I’m married it’s not just a crush it’s more like an obsession. I’m the drummer for his band he’s the lead singer. Every time I come over to practice she’s always fallowing me around she never leaves me alone. Whenever me and my wife are sitting on the couch she always sits between us. Today she laid down and fell asleep on me my wife thought it was cute. I had to tell her that I’m married she got really upset with me she called me earlier crying her eyes out. Once in a while she sends me messages saying “ I love you “. She even told me that she dreams about me and her. I feel really bad for hurting her. She told me today she thinks that no one loves her that she feels alone. Her parents died her brother is the only one she has but he’s married now and has a kid she thinks he likes his husband and daughter more than her. She said he hasn’t payed attention to her at all since his daughter was born. I would get her and our guitar player together he’s single but he’s too old for her he’s 23 she’s 11. She really likes me she said I’m her favorite band member. I feel really bad for making her cry. How can I help her ?