SSDI, Medicare snd VA Healthcare

I recently qualified for SSDI. I have received my backpay as well as my first momthly payment. I have also been 100% sercice connected T&P for years now. Social Security enrolled me in Medicare parts A & B automatically. My concern is that by having this coverage, my current healthcare situation with the VA will somehow get derailed, very complicated, and costly as ot creates a multiple payer issue. I prefer to continue my current VA coordinated healthcare. I also want to avoid copays, deductibles and cost shares and I certainly don't want to get caught in the middle of the Who pays first/second argument etc while doctors dont get paid etc. SSDI people say i cant cancel Medicare. Part B is $200 a month. Can anyone give me the simple answer pn the pitfalls of having medicare while being enrolled in VA Healthcare?