After your many years of dedicated service, I can certainly understand why you were offended by your manager's behavior. The way your manager handled your resignation seemed unnecessary and insensitive, but it is not illegal. In other words, it was lawful for your employer to ask you to leave on the day that you put in your resignation. It was also lawful for your manager to escort you out of the building. You may have a claim for unpaid overtime, however. You would need to consult in person with an employment lawyer to get a careful evaluation. Good luck.
My answers to questions posted on AVVO are intended to provide general information only, and are not intended to be legal advice. Employment law issues typically require a careful case-by-case analysis. Consequently, if you feel that you need legal advice, I would encourage you to consult in person with an employment attorney in your area.
As my colleagues say, you don't have a claim for this. You were an at-will employee. As such, you had few rights under Texas law. Here is a discussion of the subject:
For what it's worth, the law didn't require them to pay you through your resignation date. They could have just cut off your pay then and there. You may not have liked the way you were treated, but your employer did nothing wrong.