I'm so sorry, Tim. I cannot imagine what you are going through. My H is a cheater and a liar. But, he does love his sons and I would never "use" them to get back at him.
You seem like a great guy who wants to do the right thing. I wish there was something else I could think of to help you. Does she have a L? Can your L reach out to hers and discuss before you file and open the can of worms with biological dad? Maybe if her L was one talking to her the emotions would be taken out....
M 44 H 46 M 20yrs T 25 yrs S15 S12
ILYBINILWY 7/18/15 Move to MBR 9/8/15 Physical Separation 10/10/15 Suspect A 8/2015 Confirm A 12/27/15 D filed by H 2/2/16