Take it to the courts yourself. It shows that you want the children, rather than being summoned to the courts and turning up because you have to.

In Texas thier is no presumption that the mom is better fit to raise the children. You have a legitimate shot to keep them.

Men tend to win custody when they make the equivalent effort that the woman does. They're your kids, you want to see them on a regular basis? Fight for them. If nothing else you can explain it to them when they're older that you actually DID fight for custody of them, you just didn't win. Instead of having to tell them when they're older and ask you about it that, "well, daddy thought mommy was going to win either way so he decided that fighting to be the one to take care of you wasn't worth the time, effort, and money. I still love you of course, you just weren't worth those things at the time. Who wants more pancakes?"

Actually, in Texas the mom usually wins custody because the dad usually doesn't bother in the first place. If the dad actually makes an effort then the chances are skewed towards him. You'll probably be fine as long as you try & don't do anything crazy.

Speak to her about it. Make sure she knows that no matter what, you place the kids first and will always be civil and act in their best interests. Divorce proceedings and custody battles get ugly. You don't want to put the kids through that if you can avoid it.