I think you deserve a gold star for taking on this difficult "case", though a seasoned attorney might have advised you otherwise. But we'll return to this question in a moment.
I am curious if, as you say in your dream report, you have never met your husband's ex "face to face." If so, then perhaps your missing eye reflects concerns about your appearance, much as dreams of "teeth falling out" commonly do. With your relationship to the same man in common, it is natural that you both will be comparing each other, so concerns over appearance are to be expected. Also, take note of where it is that you notice your eye is missing: in the ladies room, where assessments of (and adjustments to) appearance routinely are made.
Associations to our eyes, of course, are visual. Your upcoming meeting with the former wife may be reminding you that your ability to see the past -- vis-a-vis her relationship with your husband -- is limited. In this sense you may feel at a disadvantage in your upcoming meeting. Even though you have become closely acquainted with your husband's past (through negotiating the settlement), the truth is that you still don't know, at a personal level, a great deal of information about their relationship. This "disadvantage theme" is repeated in the dream by the fact that the meeting takes place on the ex's turf -- the restaurant -- and that you are the one who is forced to wait for her, and not the other way around. Also, your husband's ex sounds like a tough woman. Perhaps you have perceived, rightly so, that she will try to exploit any advantage she can?
It also is possible that the dream is warning you about an aspect of the settlement that you currently are "failing to see", though I do not believe this is the true message of the dream. Consider that your dream does not suggest an inability to see as much as it does an attempt to cover up an inability to see. In the dream you seem to recognize your lost eye as no big deal - you write that "I get a little upset." This suggests your rational understanding that you can not see a past that you were not part of. On the other hand, the stress of the negotiations appears to be taking its toll. You wonder how much longer you will be able to keep your eye closed -- and keep your emotional feelings at bay.
Your dream reflects self-doubts as you head toward the negotiating table, but in this case the real world is more telling than your dream. Not only are you this woman's equal as a tough negotiator -- you have succeeded in reclaiming 43 percent of your husband's former restaurant -- you are with the man you love. I think you're the winner in both categories. (In the future, though, you may want to turn these "messy" ones over to a third party!)
What's the message of this dream? It's time go close the deal -- with both eyes open to recognizing your success!