I've been a vegan for several years. Vegetarian many years before that.
In that time, I've had the odd lapse - but always accidental.
This evening I was having dinner with an old lady who lives nearby. I did shopping for her when she wasn't well, and she wanted to thank me. She'd gone to the effort of making a vegetable pie. Very kind. She's a meat eater. I asked her what was in it, and it turned out butter in the pastry! She obviously didn't understand. Then turns out a bit of Lee and Perrins Worcester sauce in with the veg. That's not even vegetarian, as it contains anchovies. It was out of the oven, plate in hand, I didn't know what to do other than eat some. I took a small portion, piling my plate up more with spuds etc.
I simply didn't have the heart not to. She'd gone to the trouble of making it. But I feel pretty yucky now. I'd have felt guilty if I hadn't though, so it's difficult. Obviously, we're so incredibly privileged in the western world to have choices like this. So I won't dwell on it. I never buy animal products. But, out of curiosity, what would you have done? I have a tummy ache now too, as my body can't take dairy anymore...