If someone screenshots your private messages to roast you, they’ve shown you where the exit is.

Turning something you said in private into material for an audience is a decision about what you are to them. It takes effort: the screenshot, the crop, the choice of who to send it to. That is not a slip of the tongue, and it will happen again. The information you now have is useful, though it arrived in a rotten way.

You do not owe anybody a confrontation. Quietly stop giving them anything that could be used, and let the friendship shrink to whatever is safe. If what was shared could get you hurt at home or at school, tell an adult you trust rather than handling it alone.