While agreeing with Meathpac, I am going to indulge the OP by answering.
1. I would slow down rapidly and find a place behind the driver ahead.
2. Its your word that he did not follow the rules of the road.
3. You caused the incident by driving over the line not the other driver.
I know you think your hard done by and blaim the other driver, and in fairness if he did speed up he was acting like a prat, but thats not the point. You are responcible for your driving no one else. What ever you say about him speeding up you crossed the line not him.