I am turning 65 in May, still working and receiving medical benefits. I need some help with what to do with medical and Medicare part B.

MAKE AN APPOINTMENT with your county's Area Agency on Aging. It's a Federally funded program, but sometimes has different name in different states. They provide free counseling for people in your situation.

Many employers work insurance does become secondary to Medicare when you turn 65.
It behaves just like having a supplemental insurance. My employer hounded me the day I turned 65 to sign up for Medicare

Check with your employer. Ask if when you get Medicare does the insurance with them become a supplimental even though you are still working.

I'd look at the benefits of having both. Some insurance companies waive deductibles and other fees when you have both. Another thing to consider that you didn't mention is if you'll maintain coverage of your work insurance when you retire. Is it part of a retirement package or can you pay to keep it in retirement? As long as you are working, there is no penalty for not signing up for parts B,C,&D. Sign up immediately for part A though as there are no premiums. You've been paying those premiums your whole life via payroll Medicare withholdings. A better answer can be had with a little more info on your situation.