If you are in a tense situation, you should write a very non-threatening resignation letter. Under the Texas Payday law she has to pay you for the time worked or you can file a claim for unpaid wages with the Texas Workforce Commission.
Even if you do not have a contract, you should avoid using confidential information to take customers away.
This is not intended to be legal advice, but is only for general information. Cantact an attorney in your area for legal advice.
Some written form of a polite and brief resignation letter would be best.
If she will not pay you for the time you have worked you will need to file a wage claim with the TWC or DOL.
The clients can choose to follow you to another employer but you should be cautious about using any confidential information to retain those clients. That could include using client lists and client contact information.
i agree with my colleagues but please also remember that she does not have to let you work the last two weeks you are willing to work. Many companies have a policy of "walking" or immediately terminating, employees who have given notice of intent not to continue employment.