PLEASE HELP! Other half of shower handle is stuck

I was in the bathroom and noticed the shower was dripping, so I turned the handle off forcefully and accidentally broke it—the handle came right off.

I unscrewed the knob and valve trim and found two plastic pieces behind the knob, which I believe are part of the internal valve trim (I removed those as well). Now we’re left with two silver pieces which is the other half of the handle and then another silver tube behind it.

We’ve tried pulling or unscrewing the silver pieces, but they’re stuck. Does anyone know how to remove the other piece of the handle?