The judge will rule whether you may play the actual recording during a trial. You may waive certain of your rights against self-incrimination if you play the recording, though. Careful.
It sounds like you'd better get a lawyer. Fast.
You should be able to use the 911 call provided certain people have been subpoenaed. It sounds like you are trying to represent yourself, that rarely works out well. You need to hire a local criminal lawyer or if you can't afford one, at least have the public defender as stand by counsel for you. Your lawyer will be able to explain the rules of evidence to you and ensure the best chance if the 911 tape being admitted.
The answer is yes you can use the 911 call in your defense. However there are several steps you need to accomplish before that happens.
First you need to List the 911 call as evidence to the prosecutor.
Second you need to subpoena the witness i.e. the 911 call operator or the custodian of records who maintains those calls in your jurisdiction.
With the trial being close in time you need to do this quickly.
Once the 911 call comes into evidence your attorney has the ability to comment on his or her interpretation of that call and how it relates the facts in your case in establishing defenses for you.
It's clear that you are in over your head. You are not familiar with the rules of evidence and you don't understand the predicate necessary to admit the evidence you want. You need a lawyer ASAP. As a prosecutor, I went to trial against several people representing themselves. None of them won, but I believe several would have if they had an attorney.