What are the chances the DA can prosecute?

It is effectively impossible to predict whether a DA will prosecute without knowing all the evidence available, and your testimony may be compelled.

They will subpoena you into court and make you testify. This is if they really want to get him.

Probably slim. If the D.A. wishes to proceed, they can and will subpoena you to testify. You will be required to appear in court on the date stated on the subpoena. Failure to do so can result in the judge issuing a bench warrant or body attachment for your arrest. The police will be looking for you and when found will arrest you and eventually bring you to court to explain to the judge why you disobeyed the subpoena. The court can find you in contempt of court and sentence you to jail. If you refuse to testify, the court can also find you in contempt and sentence you to jail.

There is nothing you can do. Prosecutors will never drop charges just because the victim has had a change of heart/story. The fact is, in 95% of all DV cases the parties reconcile, and prosecutors are well aware of this. He needs a good lawyer.

Based upon what you have told me, the chances are extremely minimal. Sounds like the best place for this person is jail. I hope is NOT still your boyfriend. With his criminal history, the next incident will be even worse. I sure hope there are no kids between you.

It really depends on the prosecutor and what their policy is on handling such matters. It is up to the prosecutor and the prosecutor alone to decide whether or not to press charges, and whether or not to continue pursuing the case once charges have been filed. You will be subpoenaed to court to testify and if you refuse, you could be held in contempt of court, have a bench warrant issued, and be fined and/or jailed up to 93 days. Often the prosecutor does not like to proceed with an un-cooperative or reluctant victim, but they can and sometimes do. They may be more inclined to proceed if there was significant physical harm and if he has priors for similar offenses. You can discuss the matter of dropping the case with the prosecutor, but at the end of the day it will be his decision. I would not advise you to ignore or violate any court orders.