The answer to your question depends on several factors. What was your offense and what county did the offense occur in and who is requesting your ex-boyfriend to sign the affidavit. Many counties may still pursue a case where an affidavit of non-prosecution has been executed. However, if the county is the one requesting to meet with your ex-boyfriend I would think the chances are good that no case will be pursued should you ex execute the affidavit.
When I was a prosecutor I would consider dismissing a charge where the victim executed an affidavit of non-prosecution and I belived the victim's intention was sincere and not a result of pressure from the defendant.
As to your second question, I would wait to see if you are charged with an offense before pursuing an attorney.
Though the District Attorney's office can lawfully pursue this prosecution if the assistant district attorney assigned to the case believes that the evidence gives rise to probable cause that you committed the crime charged, it is unlikely that the prosecution will go forward if your former boyfriend freely and voluntarily signs an unequivocal affidavit of non-prosecution.
You are entitled to the assignment of a public defender or court appointed attorney only if you establish that with evidence that you cannot afford to hire an attorney. The court coordinator does not make this decision; the judge does. I do not know if the court coordinator consulted with the judge, but any competent court coordinator will know how the judge decides a request for free legal counsel.
I do not know what your financial and work situation is, but you would be well-advised to turn to every lawful resource you have (your assets, your family, and friends) before you ask for a free attorney. You get what you pay for is a maxim that holds true in this situation.
Contact the Office of the Public Defender directly.
As has been written, much depends upon the nature of the charge(s).