As long as they are paying you at least minimum wage, they can change the pay rate. While you say that you are the only male employee, you don't say how many employees there are-- only that it's a husband & wife business. If there are fewer than 15 employees, the fact that you are the only male employee is probably irrelevant (unless a state or local law sets a lower threshhold), particularly since other than saying you were the only male employee, you haven't provided any facts that would suggest you were singled out for a paycut based on your sex as opposed to economics or some other legitimate reason.
Do you have any recourse other than quitting? Sure, you can keep working at the reduced rate of pay while you conduct a job search, or until you convince them that your services are worth more.
Answers to questions are meant to be general only, are not intended to be legal advice and do not create an attorney-client relationship. Answers to questions are based on NY law, and the laws of other states may create different rights and obligations.
Without a written contract, most employees are "employee-at-will", which means that the employer can terminate you ro make changes to your pay at any time, for any reason as long as they are not motivated by your protected status (i.e., age, gender, religion, national origin). Any change in pay or terms of employment must be proactive, meaning the change cannot be for work you have performed in the past. Without further evidence that your employer is changing your pay with an illegal motive, there is nothing you can do.
I do not practice law in Texas and would recommend that you speak with an attorney in your area if you have additional questions.
Do you have any written contract that you signed along with your employer? If the employer does not have any contract with you stating that he would give you a notice with a certain timeframe, you probably cannot do anything concerning the 20% pay-cut for which you only had a three day notice. The facts available in your question are not sufficient to say that gender was the reason for the pay-cut.