Lack of understanding by employer

In my supervision a week or so ago my line manager said that she found it intimidating O was rocking in my chair and didn't like the way I was staring.This after she's had a rant about trade unions and my pre TUPE employer. She then said she could not carry on because of my behaviour.

I have consistently said I am overworked and that I am set impossible workloads. Last week I was sent an email saying my work again was piling up.  I replied saying I found it difficult to express how I felt about my work, and (since it appeared I was again being blamed for something not my fault) I said I did not like being the whipping boy and that my protests appear to fall on dead ears, amongst other things to try to explain my feelings and the workload situation.

If course, she went straight at me for this.  She found my language 'offensive' 'inappropriate' and unacceotabe. .I qcannot see in any way that expressing my feelings in this way is unacceptable, but I don't know if she really understands the meaning of 'whipping boy' as I understand it to mean a person who is blamed and punished for someone else's misdemeanours which goes back to royal courts when a bit was employed to take the punishment of a Prince since the Prince being of royal birth could not be punished. I cannot understand why she finds this offensive apart from to not address the problem in the first place as to why I felt that way. And it goes to help prove that my protests have 'fallen on dead ears ' in that she did not want to understand my reason for using this terminology.

Can anyone explain to me why this is unacceptable or offensive language?. I appear to be goaded into a position that causes me anxiety and asked to explain and then be punished for when I do. And her email to me insinuating I was not getting my work done I found offensive but if course that does not matter. I was close to a meltdown at that point but have been told my meltdowns are unacceptable too.  Rather than send me email, she would have done better seeing if anyone could help me with my work or coming to say she could see I was having difficulties and someone would help out.

I do have problems with communicating and being blunt, I cannot understand the neurological mind at all. She is now saying she is to draw up a behaviour agreement but I cannot stop being autistic, having meltdowns or being truthful in expressing my feelings.So how can I agree to something I have no real control over which is part of my being autistic?