What about me being sad that I suddenly could not eat my favorite dish?
What happened to make you unable to eat your favorite dish?
I am a huge fan of roastbeef and I liked it very much, but recently I found out that the producer of the roast beef has been killing horses.
Often, our favorite food brings us comfort due to both nostalgia and taste. Being sad that you found out the company is unethical is completely understandable. Can you find a new company that makes tasty roast beef that isn't unethical?
Alright, I will never eat roast beef again.
You'll be okay in the end, because what you're doing is for a good cause and you just need to remind yourself that. Sometimes it really feels bad when you can no longer eat something that comforts you, and that's a completely valid feeling.