Oh, and once you make the claim that you're trying to change your life in earnest, the court will look into that. If this is a good, thorough court, they'll verify your claims.
They're also going to look at who does the majority of childcare, planning, and coordinating and who has done it the majority of the children's lives, in and out of the marriage. Usually, thanks to a variety of factors, that's the mother. I heard a couple of judges say that a lot of the time, that's the deciding factor on who gets what. (This should also be a flag for dads. Get in there!) If, for example, you had a bad month during the end and spent most of your free time in bed depressed, that doesn't mean you didn't do the majority of the childcare every other minute/hour/day/week/month. Also, your "I'm changing my life" explanation addresses that.
BTW, I'm coming at this from a couple of angles. I had an epic custody battle myself [which you know
] and was also trained as a court advocate for abused kids. It takes a lot of chaos for parents to LOSE rights altogether, but it doesn't take a lot to figure out which parent is the safe, sane, stable parent and where the kids should spend 90% of their time.