If your spouse signed a formal agreement resolving all the issues, the judge may or may not allow your spouse to wriggle out of that agreement and contest one or more issues in front of a jury. If it comes down to a jury trial I HIGHLY suggest you hire a lawyer to help you with your case, even if it's just coaching you on rules of evidence and courtroom procedures if you insist on representing yourself.
This answer is for informational purposes only. This answer is not intended to create, and does not create, an attorney-client relationship. Use of this answer is not intended to create in any party any rights whatsoever. You should not rely on this answer alone for making decisions regarding your legal matters, as that requires an analysis of your specific facts in the context of existing law. It is recommended that you seek legal counsel for such matters.
You may possibly have badly screwed up. Very badly,. Get a lawyer ASAP.
As a general rule, the filing of a divorce REPLACES the separate maintenance case, and unless there was specific language in the agreement that allowed you to also use it in a divorce, there is a strong possibility, especially if circumstances have evolved and changed, that a judge may not enforce the agreement now.
Since she has a right to seek a jury trial you need a lawyer. I have had cases where with good pleadings I can strike that demand because of no answer, but that's probably an amendable defect, so the case would still go to trial.
Again, get a lawyer. It's vital in your fact pattern.
A weekly guide with tips and legal advice for each stage of the process.