I would have interpreted some of the lines differently, but your translations are mostly possible as well; however, I found a few mistakes:
"mizutamari" is one word and means "puddle"
"semete" means "at least", somewhat like "sukunakutomo", not "assaulted"
"sono koe" would rather refer to the adressee's voice = "your voice"
"soba ni ite" means "(please) be near me, be/ stay by my side"
I'm sorry to be correcting you like this, I really hate doing it because it makes me seem so arrogant and all, but then Versailles is my favourite band, so... ^^'
There are some other details as well, not quite as important, but if you want to go perfectionist on this one give me a shout, I could take a more detailed look at this one when I have more time...
The の (no) in the line "音もなく崩れてゆくのなら (oto mo naku kuzurete yuku no nara)" is not actually sung, but it is in the lyrics booklet.