Although it is convenient, and even strategic, to navigate with perfect caution around your professional relationships, failing to do so, shouldn't be perceived as a personal deficiency. To anticipate that coworkers are not your friends, to obviate that your honesty can be used against you, and disciplining your personality around your company's culture, are not signs of intelligence nor work 'ethics'.
If you trusted and opened up with some coworkers and they used it against you. If you overshared something about your personal life and now you're being disrespected. If you felt vulnerable and reached out to someone in your team, for them, in turn, to discuss whether you are a 'stopper' now. Don't blame yourself! Don't tell yourself that you were stupid and that now you're paying the consequences. Don't fall into thinking that you're inadequate for interpreting your relationships with coworkers as closer than they actually are after spending almost every day around them.
Acknowledge that, rather, you wouldn't betray a coworker, so you didn't anticipate them to. That other people's dignity actually means something to you. You are capable of treasuring the integrity of others, valuing someone based on some shit they said is unreasonable to you. So it's natural for you to assume that the adults you're working with are also quite impartial. And finally, being pragmatic is undeniably the universal equation for getting things done, but you are allowed to help or care for the people around you. People are not senseless machines without feelings, dreams, and problems, even in a professional setting.
I am not saying that there isn't anything to learn from these situations – where being yourself or transparent with coworkers was damaging. I even think that one should confront these 'lessons' open-mindedly. Meaning, taking some time to understand your social 'mistakes' and what they caused to avoid them. Nonetheless, you're not to blame for naiveness, expecting others to hurt you isn't something smart, it is just convenient. People can be bullies, but you, like everyone else, can choose your morals and how you impact people that shared life with you. Finally, you're always allowed to strive for your life and well-being, even after mistakes.