Compensation and Overtime: Can I Get Paid Less Per Hour After Leaving a Union but Staying As a Part Timer

My question involves labor and employment law for the state of: New York

I'm part of the SEIU union in Westchester, NY and I was told by my employer that I need to work a full week in order to remain in the union and have medical benefits. I can't work a full week because I have another job (non unionized), but I would like to work on part time at this job. I have been working in this place for over 20 years and I wonder if I will pay me less per hour if I leave the union.

Advice is appreciated.

Compensation and Overtime: Can I Get Paid Less Per Hour After Leaving a Union but Staying As a Part Timer