WP - first of all, hugs to you. I know this is be so hard. Some people would probably tell you not to jump to conclusions just yet, but I would be thinking the same thing as you (about why she wanted to talk). But just to look at it from another angle, do you think your W would actually bring up a conversation about filing for D the day before your D's birthday? If that is what she wanted to discuss, would she wait a couple days until after the b-day?
As far as advice, I can only tell you to try as hard as you possibly can to not say hurtful things, if indeed she does say she is going to file. If you hurt her, it will only add to the reasons she has in her mind for wanting to divorce you. Not sure if you drink alcohol or not, but what if you had a glass of wine or a beer before the talk? I did that once before I had a talk with my hubby. I do think it mellowed me out a bit and allowed me to say the things I needed to say and not be so emotional.
If she indeed says she wants a divorce, I would say something like "if you really feel a divorce is what you want, then I won't stop you, even though it is not what I want. If you are at all uncertain about it, then do not file just yet. Please be sure about this."
