It is ABSOLUTELY FINE that you recorded a closed session.
There is no means or mechanism by which you might be precluded from doing so.
The only transgression would be if you shared detail about a closed session with someone that might not have been there or be entitled to see it.
Now then, if you ‘know’ because of what you recorded, that someone is lying, then there is nothing to stop you (in fact you are obliged) to report the matter to the MO.
The solution here would appear to be, tell ‘em you know what you think they are going to state is - shall we say - “inaccurate.” Tell them you have a recording (if you want to) if they carry on its on them.
State the detail of the “inaccuracy” and state the proof that it is inaccurate and let MO fecide.
Well it would be but for the fact MO is a pointless office with no authority to actually DO anything.