In Illinois all marital property is 50/50. Her bailing all of the sudden, and the problems are all you, suggest she's got someone else on the line. The ideal would be if you could work out property separation between the two of you. If you can get evidence she's been cheating, it probably won't help you in the divorce, but it might buy you some bargaining power.

Good luck to you man. No matter what else happens, always put your daughter first.