I'm so confused and dont know what to do

My best friend is a gorgeous girl. She's got a flirty personality, but she's always had that. I found out over the weekend my boyfriend of 7 years is crushin on her. He's usually always either gone or in the bedroom with the door shut and I'm with the kids all day, everyday. Unless if she's here. Then he's always out here, and he treats her 1 year old better than he does our kids. I had suggested that he block her so i could feel a little better, and i thought he did, until i walked in on him messaging her through facebook last night. She told me last night that she's emotionally drained from both of us asking about the other. I've tried talking to him but he just won't talk to me.... So i would ask her. Now she dont wanna talk at all. What would you do in this situation? Any advice would be great....