If a fellow teacher is using the knowledge of your mistake to intentionally make you feel inferior or undermine your professional standing, it's important to address this situation professionally and assertively:

1. **Open Communication**: Initiate a private and respectful conversation with your colleague to express your concerns about their behavior. Use "I" statements to communicate how their actions are affecting you emotionally and professionally.

2. **Request Clarification**: Ask your colleague if there were any specific concerns or motivations behind their actions that they would like to discuss. Sometimes, there might be misunderstandings that can be cleared up through dialogue.

3. **Document the Behavior**: Keep a record of any instances where you believe your colleague is deliberately trying to make you feel inferior. Document dates, times, locations, and descriptions of the behavior.

4. **Seek Mediation**: If direct communication with your colleague does not resolve the issue, consider involving a neutral third party, such as a school administrator, department head, or HR representative, to mediate the situation.

5. **Familiarize Yourself with Policies**: Be aware of your school's policies regarding professional conduct and bullying. If your colleague's behavior violates these policies, bring this to the attention of relevant authorities.

6. **Focus on Professional Growth**: Continue to prioritize your own professional development and growth. Show a commitment to excellence in your work, which can counteract attempts to make you feel inferior.

7. **Support from Allies**: Seek support from other colleagues who may have observed the behavior or who can provide advice on how to handle the situation professionally.

8. **Maintain Self-Confidence**: Remember your worth as an educator and professional. Confidence in your abilities can help you withstand attempts to undermine your self-esteem.

It's important to address this situation proactively and professionally to maintain a healthy and respectful working environment. Your focus should always be on providing the best possible education for your students and fostering a positive atmosphere in your workplace.