>this kid is now in possesion of a sd card(a one with just the mother board) containing.... well, Rule 34.

>the kid is now in possession of my motherboard to a sd card containing rule 34

I'm fairly certain neither of these sentences makes sense.

Anyway, this kid is an asshat and there's a good chance everyone knows it. The principal certainly should know it.

As far as the school is concerned right now, this is bullying plain and simple. If everything you said about the problem conversation is true to the letter, you just have to explain two things to the principal. First, you were absent-mindedly answering 'yes' to every question because you wanted to be left alone but didn't have the heart to say so. Second, you were not aware of the fact that you were being recorded. Tomorrow, take a deep breath, do that, and take it from there.

Beyond that, start documenting everything now. Dates of the events, screenshots or other copies of any social media posts - anything this kid does at all with this information, you get the best record of it you can. Recording a conversation without your knowledge or consent is morally questionable at best and literally a minor criminal offense at worst depending on where you live. (Doing it on school property, at a bus stop, or at a school-organized function is almost certainly against school policy, and showing off porn and also claiming it to be yours definitelt are.) Assuming you did not, in fact, give this student that SD card, then if that claim is false it falls under slander/libel, and if it is true then the means by which this student obtained this information must have been simple theft, breaking-and-entering and burglary, or distribution and use of illegal software. It may also be defamation regardless. This probably won't go far, but don't mess around with stuff like this, do what you can to be ready now.