You have unintentionally, I suggest, created a straw man argument by overlooking the usage of the word before, as found in the passage you cite from Isaiah 43.
Jehovahs Witnesses do not believe Jesus was a god who was created before Jehovah existed. They believe Jesus was created after Jehovah God already existed. In other words, Jesus Christ was the first ...
Jesus is not a created god anymore than the men who were called gods in psalm 82:6 by Jehovah were created gods.
The context of Isaiah 43:10 is important in understanding what is being said by God here.
The following is a summary of what Albert Barns says on the subject.
In the previous chapter he had severely rebuked the Jews, as being deaf, and blind, ...
The idea that “Jesus was God’s first creation” is based on:
Colossians 1:13-16 (ESV)
He has delivered us from the domain of darkness and transferred us to
the kingdom of his beloved Son, 14 in whom we have redemption, the
forgiveness of sins. 13 He is the image of the invisible God, the
firstborn of all creation. 16 For by- him all things were created, in