how should you respond to a situation in a discussion where you're right about something, yet that other person says ' you're not '

a few days ago i was in a discussion online with someone about a politician who was prominent in the sixties, and i told him something which i know to be true about this politician, and this other guy commented ' you're not right' and told me that what i told him was false.

in a situation like that where you're right and telling the truth, yet someone says ' that's false' and doesn't believe you- how should you respond?

djjohnson · 41-45, M

Provide a source. If it’s document fact that’s the best you can do. If they don’t except that either then move on with your life.