This must have been heartbreaking. In my 30s, during my working life in the US, people did not tend to become close friends. Mostly because they were married with families and I was single. Or I was the senior person and those working under me were younger. This was in the 1980s. Perhaps workplace bullying was not acceptable then, although, I do recall at the uni I last worked at some woman in another department terrorised her boss! That was really weird. She refused to learn to use a computer and 'dared' him to fire her. What a mess. As I got older, my work confidence grew and I did not 'attach' myself emotionally to workmates.
Anyways, this is not about you or your character, it's about other people and their immaturity. Do you think they are really happy in their work? If they are like this, they must always be looking over their shoulders and at each other wondering what they really think.
You are well out of this 'circle of distrust' and are better off making a new workplace life. But keep it that way. Pleasant, companionable, but don't invest your heart in workmates. They probably have their own agendas as well. And, if this is the way they are, they will surely end up at odds with each other when the chips are down over promotions, or pay rises, more responsibility, etc.
Family and friends outside of work are much more rewarding. And if you have extra energy left over, join U3A as suggested and expand your horizons, or donate time to volunteer work. You will be much valued and make real friends.
