TxHubby, thanks for the kind and supportive words.
The new W is prioritized right to the top, I have heard similar before and making sure I do so.
As far as custody goes... I think that is far more tricky than we can summarize here. I would prefer to limit xW's interactions with the kids, but I just don't see that working. First of all, trying to get the court to agree to such would be nearly impossible. Besides her irresponsibility that lead to the issues with S12, most things she does are decent. She keeps them fed, clothed, clean, etc. School attendance has been an issue, but the rules of probation should fix that problem. If not, it will be one more reason to step up and do something.
Next issue, her bitterness. She is only slightly bitter, for the most part she just forgets about the issues. But if I take any action against her, will make her even more bitter, and it will likely affect the children. Their visits will turn back into "bad mouth their dad" sessions.