I understand OP, I have been vegan for 8 years now and sometimes I just want an egg.
I think over time we become desensitised to the reasons that made us vegan in the first place and we lose that emotional reaction to the suffering and abuse animals are put through.
You could follow Singer's Paris Rule - be ethical and vegan but treat yourself in Paris aka when you're in holiday. I've done this a few times with mixed results. Once I was DYING for a croissant, only to find the butter overwhelming and feeling sick after. I've craved Ben and Jerry's ice cream and had a bit, only to feel overwhelmed once again by sweetness, it was sickly. I once came home drunk and ate an entire plate of fried chicken which was sitting on the side and that really hit the spot, unfortunately. I had a tiny bit of buttercream frosting at work only to find that it tasted bland compared to my vegan pistachio cake. In short, if I reverted I would likely be dairy-free but eat meat.
These days I manage by ensuring that I eat really good food. I learn a lot of recipes and I get excited about my next meal, about what baked treats I'll be making this weekend and I order fake meats and cheeses and chocolate online to have as a treat.
Today for instance I had a chickpea of the sea sandwich (vegan tuna basically) whilst my colleagues ate stinky fish, chicken and rice, a microwave meal which was a sea of fat and grease, and a cheese sandwich. Faced with that, I was glad I had good food which I had to get creative about making instead of "choosing" something easily available which was unhealthy or boring or something I had had a million times before.
Last night I had vegan bangers and mash with onion gravy, tonight DP is making a stir fry with all the vegetables in the fridge. This weekend I made chocolate cookie sandwiches. I had a strawberry and vanilla ice cream sundae that I made at home. I went to the Vegan Hippo in Soho and had their kebab sticks which were DIVINE. Much better than charred meat.
Basically, I'm making sure that I don't get a chance to envy others' non-vegan food now that I'm basically desensitised to farming practices on an emotional level. Maybe this approach could work for you, too?