Pick one, because they all say the same thing, forever, eternal, without end.Which Bible did you use?
The same forever that describes God's attributes in Psalm 136, describes Satan's stay in the Lake of Fire. Both are without end.
What you have done is revised the Bible to suit your understanding of it. You added to it. You added that forever, and forever and ever, and eternal actually have a time limit. And, then went on to decide that Satan would be given a reprieve and the vitriol between God and Satan would mend. That everyone, humans, and fallen angels, and demons all live happily ever after with their buddy, Jesus.
Your premise simply is not Biblical.