Pesky Instant Messages for the Middle Man

Dear Cyber Sorter,
My flatmate’s ex-girlfriend is stalking me on Facebook. I live in a shared house and I’m always friendly with visitors but this woman takes the biscuit. She broke up with my flatmate about three months ago, breaking his heart. After a couple of weeks’ silence, I was on Facebook when a chat message popped up from her saying, “Hi”.
I ignored it, knowing what was coming and sure enough another one pinged. “How’s John? I've been a bit worried about him.” 
This is all none of my business, but she’s forcing me into the middle of it by showing her concern to me and not him. Do I tell him about these messages or is it better to leave it alone? I wish she would just leave me out of it.
GB

Dear GB
You should leave her out of it. De-friend her. Although it might feel like a horrible thing to do, it removes you from the situation so she can’t ease her conscience or play her games or whatever she’s doing through you.
It will force her to either contact him and make reparations or leave him alone to get over it. Neither option should involve you.
It’s also not nice for her to see you online, send you messages and get no response.
You could just switch your chat status off so she can’t see when you are online. But really, why stay connected to her online when she’s not really your friend and is making you uncomfortable?
If she can ditch her boyfriend of two years, then you can ditch her, your flatmate’s ex-girlfriend