Where in the Bible are you coming up with idea that souls are eternal? Until I read it for myself, it sounds like you are making claims without backing them up with Scripture. And that's part of your problem here, thus why you are asking----how can someone who is destroyed be tormented for ever? The reason you are asking that is because you are assuming all souls are eternal.
When it comes to something involving eternity, only one of the following two options can fit with something that exists forever.
A---shall never be destroyed
B---to destroy
Daniel 2:44 And in the days of these kings shall the God of heaven set up a kingdom, which shall never be destroyed : and the kingdom shall not be left to other people, but it shall break in pieces and consume all these kingdoms, and it shall stand for ever.
It's as simple as this, with eternity in mind. Only 'never can be destroyed' can mean to exist forever. To destroy can never mean to exist forever. But if I am wrong then prove it with Daniel 2:44 by showing how both A and B above can mean to exist forever in that verse. And if you manage to do that, I will change my position just like that, thus agree with the position of ECT instead.
Literal translations of the Hebrew and LXX (which uses the word AION, age) say for Daniel 2:44:
'And in the days of these kings raise up doth the God of the heavens a kingdom that is not destroyed -- to the age, and its kingdom to another people is not left: it beateth small and endeth all these kingdoms, and it standeth to the age. [YLT]
In their days, that is, of these kings, the Eloah of the heavens will set up a kingdom that for the eons shall not come to harm. His kingdom shall not be left to another people. It will pulverize and terminate all these kingdoms, and it shall be confirmed for the eons. [CLV]
And, in the days of those kings, shall the God of the heavens, set up, a kingdom which, to the ages, shall not be destroyed, and, the kingdom, to another people, shall not be left,—it shall break in pieces and make an end of all these kingdoms, but, itself, shall stand to the ages. [RO]
into the eons, i.e. ages (APB Greek English Interlinear, LXX):
Study Bible - Online Greek Hebrew KJV Parallel Interlinear Tools
Additionally, the early church accepted the following Greek OT translation of the Hebrew OT of Dan. 12:3:
καὶ οἱ συνιέντες ἐκλάμψουσιν ὡς ἡ λαμπρότης τοῦ στερεώματος καὶ ἀπὸ τῶν δικαίων τῶν πολλῶν ὡς οἱ ἀστέρες εἰς τοὺς αἰῶνας καὶ ἔτι[and further]
Notice the words at the end saying KAI ETI, meaning "and further" or "and still" or "and yet" & other synonyms.
eti: "still, yet...Definition: (a) of time: still, yet, even now, (b) of degree: even, further, more, in addition." Strong's Greek: 2089. ἔτι (eti) -- still, yet
εἰς τοὺς αἰῶνας καὶ ἔτι means "into the ages and further" as a translation of the Hebrew L'OLAM WA ED[5703, AD]
So "the ages" (i.e. eons) of Daniel 2:44, in the context of the book of Daniel, can be interpreted as being finite. For Daniel 12:3 speaks of what is beyond "the ages".
More examples re aion/ios (& olam) being finite:
Eternity in the Bible by Gerry Beauchemin
12 points re forever and ever being finite:
For the Lord will NOT cast off FOR EVER:
aionios life, 2 UR views, eon/ian ends, millennial eon, 1 Jn.1:2, Chrysoston, Origen, Dan 12 2-3:
how do people who believe in eternal torture in fire
John 3:36, 3:16, 1 Jn.1:2, aionios life:
Augustine's ignorance & error re Matthew 25:46
Rev.14:9-11 & 20:10 & forever & ever a deceptive translation:
If endless conscious torments were true, is God a monster?
Have you been decieved by your Bible translation?
For the Lord will NOT cast off FOR EVER:
Augustine's ignorance & error re Matthew 25:46