Being mistreated or harassed at work is disorienting in a particular way. You spend a significant portion of your life there, and when that environment becomes hostile, it can shake your confidence, your sense of safety, and your ability to trust your own perceptions. Many people who've experienced workplace bullying find themselves questioning whether it was really that bad, or whether they somehow contributed to it. It wasn't, and you didn't.
Therapy offers a place to process what happened without minimizing it. You can work through the self-doubt, anxiety, or anger that tends to linger after this kind of experience, and begin to rebuild a steadier sense of your own worth. If you're still in that environment, a therapist can also help you think through your options and protect your wellbeing while you figure out your next steps.