Hi TnD, our sitches are pretty similar, only the roles are reversed. My W and I still live together in SBRs too, and W spends as much time out of the house as she can. Doing her thing, I guess. I feel bad for the kids because they've been acting out as well. Especially with W. I think they're trying to get her attention, because even when she's home, she's not really "available", if you know what I mean.
As for dads who walk away from their kids...well... IDK your H, but I don't have much respect for them as a group (hence my user name). But, speaking from experience, your boys will one day understand how hard you worked and how much you sacrificed to provide for them. But it's good to encourage your H to participate in their lives because not having a dad will leave a hole in their lives that will be hard to fill.
Stay strong and don't give up.
M41 W42 M 12 T 15 S10, D9, twin Ds 3 1/2 BD 1/2/2013 Living as roommates Working on D agreement w. mediator 5/13