Bit complicated but I was seeing someone I work with on and off for almost a year. My Dsis was pregnant but unfortunately had a miscarriage. I told him about the good news when she was pregnant but we split for good and haven't spoken since and then my Dsis had her miscarriage. I have my work ball on Friday and when we last spoke she wasn't coming because she was pregnant but now she is coming as my guest. Obviously he doesn't know and I'm worried he is going to get drunk and make a comment about her being pregnant and not knowing the situation. Shall I tell him before the ball to save any awkwardness and upset on my Dsis behalf?? I did tell him I didn't want to speak to him unless it was work related. So should I leave it or should I tell him on the situation