Tough break. But the pessimists here are probably accurate. You should erase/harvest your laptop content before the meeting.
If you use Outlook, export the content as a .pst file to a thumb drive:
File -> Import and Export... -> Export to a file -> Personal Folder File (.pst)
Your contacts and notes will come handy in your next job search.
Don't worry about deleting personal emails, they have them on the server anyway.
If you can, run a utility program like Glary Utilities (free) from a thumb drive if necessary and use the Privacy & Security Module to zotz out everything about you internet use as well as to completely wipe erased files.
Admit nothing because it won't change their minds. Don't sign anything in front of them. Tell them you want to discuss with a lawyer first. (even if it's a bluff.) They may be fishing for chicken-shit reasons to terminate you without severance and unemployment benefits to save money downsizing. So the lawyer consult after the fact may be worth it to clarify your rights/options.
Depending what the law is your state, you could turn on your smart phone voice recorder before you enter the meeting and have it running in your pocket. (turn the ringer off.)
Good Luck...