What can i do if I have been accused of two hit and run violations and the police are threatening to arrest me if I don't come and sign the citations?

I think it's really urgent that you contact an attorney about this, as soon as possible.  I wouldn't want to even guess about the best course of action here, without knowing a lot more of the details.

Any situation like this is difficult, and sometimes it's a bit of a tightrope walk, because to a certain extent, at least, you need to cooperate with the police, but you may well not want to cooperate with them any more than absolutely necessary.  You need a lawyer's help to know exactly what you do, and don't, have to give the police.  You cannot rely on law enforcement to give you an impartial view of the law;  cops will usually state "the law" with complete confidence, but they are by no means always right.