There is no "legal" separation in Texas - there is separation with court orders and a separation with no court orders.
If she is working and able to support herself, and there is no allegation of abuse, then you will not likely pay alimony when you are divorced.
If you are talking about temporary support while you are separated, again if she can support herself and you are supporting yourself then there is not a big chance that the court will order payments during the separation before the divorce.
Although I have answered the question to try to help you, you should consult with a lawyer in your area in person on the matter. In addition, my answer does not establish an attorney-client relationship between us.
Under Texas law, spousal support is ordered in relatively limited circumstances. With the information you have provided it is not possible to give you a definite answer. However, it sounds like a little bit more information would allow a yes or no answer.
It occurred to me when reading your question, you may want to file for divorce soon if you intend to have the divorce take place where you reside. I would need more facts to determine possible venue. Just a thought.
If you wish to handle this on your own I understand. If you would like a free consultation over the phone, I would happy to discuss the general process with you. You may qualify for free legal aid or find that hiring a lawyer is reasonable. 713-826-9053