I am so sorry that your situation isn't any better. You did the right thing by informing the principal and teachers of the home situation. At least they are now aware of what is going on and can be more supportive of your children.
You are doing the right thing by speaking to a lawyer and protecting yourself, your children and your financial situation. I know that you didn't want to do this, but there are times when we are forced to do so. Listen to your lawyer and do not engage w/your wife any more about the financial and custody issues. Allow your lawyer to do the job that you've hired him/her to do.
Please take care of yourself and continue to do your GAL activities.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.