That's remarkably good French for a non-native, in my opinion.
je m'apaisais / emportais -> sounds good, but you'd need the simple past there (losing the ending "s")
However, I think the metaphor of a growing plant is lost there: "my wrath did grow. And I watered it in fears night and morning with my tears, and I sunned it with smiles, and with soft deceitful wiles."
You catch up in the next stanza, but the bit in between is hard to get.
I like the inventive way you rendered the first stanza very much, but that makes connecting the wrath with the next stanza difficult.
Just to suggest a way out:
Moi, fâché contre un ami
Le lui disant, je m'assagis
Monté contre un ennemi
Le taisant, moi, je fus pris
D'une rage que... (now you can nurture the wrath :) )
On m’en priva discrètement -> "on" might be ironic (some unknown person, knowing very well it was him) but "il" would work too and might be easier to get
L’auteur -> I suppose the idea is "l'auteur du vol/méfait", but that's a bit hard to get too. Also "tué" is not quite right, it would be like "slain", something odd to say for someone being poisoned.
The English talks about a foe, you could just use something similar like "l'ennemi mort", or maybe "le coupable mort", to keep this idea of "auteur". I suppose you could also use "vaincu" in this context, though the idea is different.
Valeriu Raut
Laplage

