To me, the boldfaced part of 'don't get me started' looks like a causative because of the form:
get + object + past participle
and the meaning:
More often, the intent is negative and the expression is used to express exasperation or strong dislike, etc. There may [be] an element of warning in it: If I start talking about this, I’ll never stop!"- Idioms Online
I'd say that, in a way, the idiom implies that the subject of this imperative sentence may cause the speaker to start endlessly talking about something in an extremely emotional way just by mentioning the topic.
At the same time, this meaning is closer to causative 'make', which uses a different grammar pattern (make +object + infinitive).
So, I'm in doubt about grammatical category of "get me started" in the mentioned idiom.
Please advise whether my reasoning appropriately places it in the causative category, or is it some different piece of grammar?
P.S. I've looked through the forum, Michael Swan's Practical English Usage, consulted some other resources, and, naturally, Googled it, but none of that has brought much clarity, hence, posting the question.