If live in a different state than my soo- to-be ex-wife, can I get joint custody of my kids?

Texas actually has several provisions which favor joint custody.  Even though everyone would like a fifty-fifty split of the kiddos, it's just not feasibly possible.  What the courts ususally do is award joint conservatorship (custody), give both parents all the same rights, but then appoint one person with the right to determine the residence of the child.  This parent will usually have the child during the week and the other parent will have standard visitation, usually the first, third, and fifth weekend of every month.  If your ex- lives in a different state, a similar schedule will be implemented, but someone will have less access.  Who gets to decide the residency of the child and who just gets visitation will depend on what is in the best interest of the children.  This will be based on a wide variety of factors including the abilities of each parent, the income of each parent, any special needs of the child, the historical arrangement involving the children.  This is not an exhaustive list.   If you want custody, and be able to decide the residence of the children, you'll need to petition the court and be prepared to make a case regarding why the kids should be left with you most of the time.