Who knows what she is thinking. But my adivce is keep documenting everything. make the judge's job easy, have a very clear, consistant story for the judge. Don't muddy the waters. "My W has shown she cannot provide a safe home for my kids." End of story. Go for full custody. If you say, she can't provise a safe home, but you are OK w/ 50/50 you contradict yourself. A judge will do what they see fit, but if you contradict yourself you will end up with less, and your kids will suffer.
Also, avoid going out with your lady friend at night. Be up front and tell her exactly why. You want your kids and your STBXW is trying to use her against you. It isn't fair, but someitmes life isn't . She will understand.
M:37 W:34 M:4 years T:6 years No Kids A disclosed - 9/1/2010 W asks for separation - 10/19/2010 Moving on - 10/24/2010 A ends (and I believe her) - 12/2010 Content - 3/1/2011 Served - 3/18/2011 D Day - 6/20/2011