First thing to do is calm right down!
1st thing I would suggest is to find some time to do some exercise.
What I would say is that, you know the weeklies are gone. SO now its just damage limitation.
When you go for your meals, either announce loudly to everyone several times that you will not be having pudding AT ALL, or eat as lightly as you can and try and share a pudding with someone.
Trying to point a sunday lunch is not easy if you haven';t made it (I make and weigh mine, so its easy). You could try looking at SUnday lunches in commercial pubs like Wetherspoons if you want, in order to work out the points. Go easy on the roasties.
I would eat a small handful of haribo if i were you, at the end of the afternoon. To give yourself something to look forward to> I have a tangfastics problem, so I know it's hard.
When these social meals are over, draw a line and get back on plan. Do some exercise, drink a load of water.
You might not lose on Tuesday, but you can arrange it that this doesn't derail you too much!
Let us know how you get on! x