Trust N Respect

Hi coaches, I read the question about trust n respect. I have the same question. Can you please elaborate more how I can build up trust in myself when I need to have contact with a person who didn’t show to be a trustworthy! Should I put a boundary not asking him to do anything for me? Or not getting information from him since it is not reliable? I am still confused how I need to think about him and behave ? Normally I remove the person from my group n ignore or be indifferent about him. But the thought that he is not trustful is still there. Thanks