Certainly evil exists and certainly God is not evil nor did he create evil; he allows it. But why? And what is his experience of all this?
The origin of evil is free will; of allowing created creatures to choose what they will do.
Evil is not a created thing, rather, it is a condition of a living soul, an attribute of the soul. Physical creatures each have a soul residing in the spiritual realm and each spiritual creature (for example, an angel) also has a soul residing in the spiritual realm. Each soul is capable of free will choices and, thus, can create evil.
God does not see into the inner recesses of the soul nor does he see the motivators for its free will choices. God does not read our thoughts nor does he see evil.
To avoid thinking about all this, many Christians claim evil is not really anything at all; it's merely the absence of good. This is absurd! Evil is a spiritual power, a living force, an expression from a wicked soul.
God experiences each soul's interaction with God himself; each soul communicates with God in some way or another. Souls in distress call out to God and he acts to comfort them. Souls needing eternal redemption call out to God and he sends them saving grace to save them which they appropriate through faith.
Free will choices can be performed which please God or which displease God. We should seek to perform free will choices pleasing to God.
The more contaminated a soul is in sin, in evil free will choices against God's perfect will, the further away that soul is from God's presence. Sin repels us away from God just as with a magnet. The further away the soul is from God, the less he hears its cries and the less it calls out to him.
When you come into the presence of God one of two things occurs...
Thus, there is a "universe of evil", a spiritual realm completely outside of God, uncreated by God and invisible to God (but allowed by God). Souls are capable of residing within this realm. Humans and all other created creatures of this universe are partially immersed in this evil realm as a result of Lucifer's fall. Ultimately in the new heavens and new earth we will be redeemed from this fallen realm. However, it will continue to exist as the lake of fire.
Free will choices opposed to God's will provides the domain of Lucifer in which he could "become like the most high". In this domain he rules, free from God's intervention, for God does not inhabit this realm.
God will not experience the pain and suffering of those in the lake of fire. He will hear their distant cries for help and as he showers grace upon them they will fade into the mists as their unredeemed hearts continually reject God's love for them. For those, it will be a continual ebb and flow of calling out in their anguish for help, then rejecting God's offer of unconditional love as they flee back into their self-chosen misery. This process will provide a brief bit of comfort to them to distract them from their misery; it will, in the end, be a form of worship of God.