Verbal warning based on student complaints without evidence and investigation
Your question does not specify where in the world you are, but the behaviour you are describing from the students and staff sounds extreme.  It also sounds like your boss perceives you to be the cause of the problem and it sounds like they are not treating you well.  In such a case, your future at this institution might not be a good one, and it might be a good idea to consider looking for a position elsewhere.  Before you get to that point, I will make a couple of suggestions for what you might do here.
As a starting point, it might be useful to invite another academic to attend your lectures to observe what is going on.  Choose someone you respect as a good lecturer who has a good relationship with you, and ask them if they wouldn't mind coming along to a few of your lectures to observe.  This would have three purposes: (1) to see if you are doing anything wrong that would provoke such extreme behaviour; (2) in the event that you are not doing anything wrong, to act as a witness of what is occurring from the students; and (3) to give you advice on how you can improve your class (either by improving your own methods, or improving student discipline, or both).  The presence of another lecturer might alter the behaviour being observed, which is unfortunate, but even in that case the observer will be able to give you feedback on what you are doing.
Once you have had another lecturer observe your class you will be in a better position to determine whether you are contributing to the problems from your students, or whether these are just unruly students who are behaving badly without provocation.  You might also be in a better position to engage with your boss in relation to the problem.  (For example, you might now have another lecturer who can come along to meetings and give their observations of your class.)  Depending on what country you are in, there may be some rules for unfair disciplinary action or unfair dismissal.
Your proposal to write a minute and send it back to your boss might be okay, but only if the minute is written in an objective manner.  If the minute is just your characterisation of the way you were treated then it is unlikely that your boss will consider it an accurate statement of the meeting, and it might just further inflame the situation.