Need advice

First, work Christmas lunch is being held on Thursday, I signed up and making lasagna and now i see that OW has signed up also. When I had the argument with H I told him to tell her not to attend and H said he can't tell her what to do. (H is not going) In anger I said I then cannot be responsible for what I say then. I do not want to back out of this lunch. How should I handle it that day? What I would like to do is expose them (I can't), take her pie and dump it on her head (I would get fired), so I need some viable advice on how to handle this! I do plan on making one portion size of the lasagna (H's favorite) and just leaving it on his desk. I know OW will have a fit if she stops to see him. teehee.
Help.


Me 53
H 50
D16, D29
M 22 years
bomb 7/08 INH - alien pod replaces H
8/08 - OW (direct report), I work there also
bomb II - H moves 10/1
expose ow 10/22
D to be final 9-09