Ok, Need some advice real quick.

My stbx just called to say he's attending D16's chamber music concert at school tonight - AND THAT HE WILL BE TAKING OW.

Now, he's not even told the kids her name yet - nor that she is an old family friend.

So when D16 takes her seat - in the small room amongst the 30 or so girls and audience members, there will be daddy sitting with his paramour and there will be mummy sitting in the same space.
WTF???

I went off to him on the phone when he told me. He ended up hanging up and then called back 30 mins later to say that he wouldn't go.

Thank goodness... BUT THAT OW WOULD STILL BE ATTENDING - as her niece was playing twinkle twinkle or some such BS on a flute.

I cracked up again and said that I wouldn't be able to contain myself If i had to front that b..tch (she was an old friend but i haven't seen her since I heard of their A several years ago).

What should I do???
PLEASE - I NEED SOME QUICK ADVICE - I have to go in about 2 hours.

The concert is about an hour in duration and is in a small music room in D16's school. I will be seated within swinging distance of OW.

How do i do this?