OK the whole chapter so we can consider the verse in context and who "I am he" is referring to and more important if Jesus and the Father are one.
Isaiah 43 (New International Version)
Israel's Only Savior
1 But now, this is what the LORD says—
he who created you, O Jacob,
he who formed you, O Israel:
"Fear not, for I have redeemed you;
I have summoned you by name; you are mine.
2 When you pass through the waters,
I will be with you;
and when you pass through the rivers,
they will not sweep over you.
When you walk through the fire,
you will not be burned;
the flames will not set you ablaze.
3 For I am the LORD, your God,
the Holy One of Israel, your Savior;
I give Egypt for your ransom,
Cush and Seba in your stead.
Who is the LORD, your God?
The Holy One is Jesus Mark 1:24 Luke 1:35 John 6:69 Acts 2:27
The Saviour is Jesus Titus 1:4 Titus 2:13 Titus 3:6 2 Peter 1:1
4 Since you are precious and honored in my sight,
and because I love you,
I will give men in exchange for you,
and people in exchange for your life.
5 Do not be afraid, for I am with you;
I will bring your children from the east
and gather you from the west.
6 I will say to the north, 'Give them up!'
and to the south, 'Do not hold them back.'
Bring my sons from afar
and my daughters from the ends of the earth-
7 everyone who is called by my name,
whom I created for my glory,
whom I formed and made."
Who created us? The "LORD, your God"?
Jesus John 1:3 John 1:10 1 Corinthians 8:6 Hebrews 1:2
8 Lead out those who have eyes but are blind,
who have ears but are deaf.
9 All the nations gather together
and the peoples assemble.
Which of them foretold this
and proclaimed to us the former things?
Let them bring in their witnesses to prove they were right,
so that others may hear and say, "It is true."
10 "You are my witnesses," declares the LORD,
We are witnesses to whom? The "LORD, your God"?
Jesus Acts 1:8 1 Peter 5:1 Acts 1:22 Acts 2:32 Acts 26:16
"and my servant whom I have chosen,
so that you may know and believe me
and understand that I am he.
Before me no god was formed,
nor will there be one after me.
11 I, even I, am the LORD,
and apart from me there is no savior.
12 I have revealed and saved and proclaimed—
I, and not some foreign god among you.
You are my witnesses," declares the LORD, "that I am God.
13 Yes, and from ancient days I am he.
No one can deliver out of my hand.
When I act, who can reverse it?"
God's Mercy and Israel's Unfaithfulness
14 This is what the LORD says—
your Redeemer, the Holy One of Israel:
"For your sake I will send to Babylon
and bring down as fugitives all the Babylonians,
in the ships in which they took pride.
15 I am the LORD, your Holy One,
Israel's Creator, your King."
Who is Israel's King? The "LORD, your God"?
Jesus Matthew 2:2 Matthew 27:11 Matthew 27:29 Matthew 27:37
16 This is what the LORD says—
he who made a way through the sea,
a path through the mighty waters,
17 who drew out the chariots and horses,
the army and reinforcements together,
and they lay there, never to rise again,
extinguished, snuffed out like a wick:
18 "Forget the former things;
do not dwell on the past.
19 See, I am doing a new thing!
Now it springs up; do you not perceive it?
I am making a way in the desert
and streams in the wasteland.
20 The wild animals honor me,
the jackals and the owls,
because I provide water in the desert
and streams in the wasteland,
to give drink to my people, my chosen,
21 the people I formed for myself
that they may proclaim my praise.
22 "Yet you have not called upon me, O Jacob,
you have not wearied yourselves for me, O Israel.
23 You have not brought me sheep for burnt offerings,
nor honored me with your sacrifices.
I have not burdened you with grain offerings
nor wearied you with demands for incense.
24 You have not bought any fragrant calamus for me,
or lavished on me the fat of your sacrifices.
But you have burdened me with your sins
and wearied me with your offenses.
25 "I, even I, am he who blots out
your transgressions, for my own sake,
and remembers your sins no more.
26 Review the past for me,
let us argue the matter together;
state the case for your innocence.
27 Your first father sinned;
your spokesmen rebelled against me.
28 So I will disgrace the dignitaries of your temple,
and I will consign Jacob to destruction
and Israel to scorn.
I have highlighted a few points from the chapter. There are more.
For me there is overwhelming evidence that Jesus "and the Father are one", that Jesus is God "with us" to say that Jesus is "my Lord and my God".
For JWs there will never be enough evidence until the WT has "new light" on the matter. As it is, the darkness is getting darker and darker. Jesus was to be worshipped and equal to God according to the WT. Now they have demoted Him to being "a god", and a created being :(
All the best,