8 calls this week, threatening my girlfriend with a felony arrest warrant, if she doesn't contact them by 3:00 pm this afternoon (April 1, 2016). Say that bond will be a $10,000 cash.

The woman on the other end, was rude and unpleasant, and became belligerent when I told her that I contacted Harris County District Attorney, Harris County Sheriffs Department and the Office of The Secretary of State of Texas.

I just got a call from them threaten me to do the same thing. What should I Do??

The things that people come up with like wth...

Threatening arrest and demanding immediate pay is illegal.  Any legitimate collection agency would know that.  Most likely you have a fake debt collector.  Read about differentiating between real and fake debt collectors here:
https://www.consumer.ftc.gov/articles/0258-fake-debt-collectors