Advice for dealing with police needed

A few weeks ago I had a row over the phone with my (then) boyfriend which culminated in my sending him some texts that in retrospect I realise I shouldn't have sent.  He phoned the police claiming to be concerned about my well-being.  I was quite upset about the row but had been working on calming myself down when the police suddenly turned up at my house and started talking about sectioning me or taking me to A&E which of course freaked me out and made me get upset all over again.  It took me about an hour and a half before I could finally convince them to leave. 

I explained that I was autistic and that I just needed to be alone and have some space and quiet and I would be fine, but of course, I am not qualified to speak on my own behalf because everybody in the world knows what is best for me and what I think doesn't matter...

Does anybody have any advice for future situations when I know that I am having a meltdown and I just need to be left alone as to how to get people (whether the police or any other "well-meaning" individuals) to believe what I am saying and leave me alone and stop "trying to help"?

Thanks...