Oh Serendipity I am so sorry, it's heartbreaking. I hope you can take comfort in knowing that you did everything you could for Charlie and I'm sure he knows that too and how much you loved him. I'm sorry it was such an unpleasant experience for you at the vets, that must have made it worse than it needed to be
Charlie was one of the first hamsters I read about when I started looking in to getting mine and he was such a special boy and so full of character.
I'm struggling to know what else to say as it's just so sad, so I'll send you some big hugs instead xx
Play well at the bridge Charlie xx