When Smokey the Elder was diagnosed with cancer 6 years ago, I told some co-workers about it. They asked if I would have her put to sleep. I said that: a. only if her life become unbearable and b. I don't believe in disposable pets. Unlike your case, there wasn't any malice intended; the one lady who loved her dog to bits realized it was the same with me and my cat.

My coworkers were supportive after I "educated" them, unlike your clueless colleague.