Don't forgive her debt... Make her be responsible for it...
My ex charged up some credit cards without my knowledge when we were married... I didn't find out until the bills came in the mail... The first time she did it, I paid them off and told her that if she did it again, I would not pay... She did it again and I kept my promise not to pay it... That eventually came out of her settlement in the divorce.... Document the debt that she's responsible for and let the attorneys figure it out...
Get a good lawyer...
Don't bring the kids into the divorce... Do not say anything negative about the wife to them, keep it to yourself... Trash talking the wife in front of the kids will just make them hate you, not the mother... The kids will respect you more when it's all over if you keep them out of the middle...
Don't give the wife any settlement money directly, or it won't 'count'... After the court sets up the payment plan with the state, then pay all the money to the state and let them pay the ex... That way you get credit for your payments...
Talk to the kids to let them know that they are not the cause of the divorce, it's because you and the wife cannot get along any more... You don't want them thinking they are responsible for the divorce... Like I stated earlier, don't trash talk the wife to the kids...