Asking how many fathers has won custody anywhere is impossible to answer. Texas has the highest rate of fathers getting custody, because of the ability of have jury trials. But, they’re expensive and than there is the problems of attorneys tell a father not to go for custody because “fathers don’t win custody in this county.” This statement is not based on any evidence to that effect, but the fact that attorneys are taught in law school not to promote the idea that a father can win custody.
The main thing is to take the time to prepare. Don’t rush into it. Gather your evidence over a period of time to show a pattern. Yes, this may not benefit the children right now, but neither would jumping in too soon and losing. Do your sons spend some period of time with you during the summer? Say like a month or more. Start keeping detailed records and be ready to file the day the day you pick up the boys. If you do it too soon, one of the first problems you will have is she will begin denying you access to the children.