My Japanese isn't great, but here's my take:
憎しみだけ裏切らないで支えてきたわ、これは真実。
"Only hatred doesn't betray me, and has supported me, this is the truth"?
I think で could be used as a connective here, but I don't understand what the きたわ ending to 支えて means.
From what I've learned, the きた is the grammar form where something has come to be over time, for example 暑くなってきた means it has become warm over time. I agree with N-Forza's interpretation.
2nd:
この手にした火は世界をそう消滅させる力なの？
Really not sure here...
この手にした火は... ＝ "the fire in my hands..."?
A rough guess would be that this means "Does the fire in my hands have the power to make the world disappear?", but that doesn't seem right.
There's also a variant which goes "この手にした火は自分でそう焼き尽くすためのものなの！" as well, with roughly the same level of confusion.
手にする is generally having in one's hands or, less literally, possessing or obtaining something. Since the the sentence uses the past test した, I would lean more towards the latter definition and go with "This fire I've obtained" rather than "This fire in my hands". 消滅させる uses the causative verb tense, meaning that the subject of the verb is making or letting the direct object do the given action. Something like "this fire makes the world terminate", or less clunkily "this fire destroys the world". However the sentence is further used to modify the word 力, so I'd interpret this sentence as "This fire I've obtained has the power to destroy the world?" The variant sentence seems to go something like "This fire I've obtained is for the purpose of burning all to nothingness!".
3rd:
赤く頬染めた如何わしい奴らも消えればいいのにね？ - I don't know what the 奴ら is referring to here
赤く頬染めた如何わしい奴らも飲むのもいいかもね - I don't know...anything about this, after やつらも飲む...
"Those suspicious guys blushing red, it's fine if they disappear, right?"
"Those suspicious guys blushing red, swallowing them might also be fine."
Since I don't know the context, this is my best guess.
EDIT:
Looking at your lyrics so far, this seems to make sense. I wouldn't say say that they're being allowed to drink since the verb form used, 飲むの, means drinking (or as in my above interpretation, swallowing), as opposed to 飲ませる, to allow to drink.
Lastly...
蓮菜の水浴びれば 壊れるよ = "Bathing in the water of the lotus green will destroy you"?
(Just a check with this one, れば verb ending works the same way as のなら ／ ならば etc.?)
れば is typically conditional form: if ... then ... So I'd interpret the sentence more like "If you bath in the water of the lotus green, you will be destroyed."
