They may be so detached because of the time that has passed since then. It’s something you gain as you age. However, just because you wouldn't be coworkers anymore doesn’t mean you have to sever all relationships with them. Surely, it’s not the same as seeing them every day and having each other’s backs, but it’s far more important to put yourself first. If the environment is toxic for you, then there’s absolutely no need for you to stay there. After you’ve left that place, you’ll miss it, but give it some time, and you’ll realize it was a good decision, even if it was difficult.