Guilt is only emotion you have many more use one of them like be happy you're not a twat like them, don't piss about and get to keep your job, it's entirely their own choice, they're not kids, age wise anyway, what would happen if you didn't report things and it got found out ?, bet you'd be in the poo, as they say you can lead a horse to water but can't make it drink, it's their choice you've already tried to help them.
tabetha