Overeating when I am out !

I have started the stop over-eating program and I’m doing good following my protocol.
But yesterday I was invited to a friend’s place and she usually likes to eat.
She served some crips and I did not want to eat them and stayed away from it.
But then my friend opened a bottle of champagne and cooked a gigantic meal for me.
I tried to stay focused on the veggies and the haloumi cheese but then my friend felt a bit hurt that I did not eat everything she cooked.
I could not plan in advance and therefore I ended up indulging with ice cream…
How can I manage to stay in control while eating at friends?