If God is sovereign over all things, and everything including the Fall came about by his will, then why should I care about anything?
I never had a choice whether or not I existed – he created me a sinner, why should I care? And, if God is sovereign why should he care either way? He is only getting what he wants.
I am very confused, and I need to repent of this – but God is not willing repentance in my life right now.
Your question assumes that you should care about something only if it is not determined or only if it is not controlled by God. This premise is necessary for your question to be rational or to make any sense. Therefore, unless it is established, your question is arbitrary, random sounds in the air with no logical connection. Why should anyone care to answer it?
It is important to establish the assumption not only to make someone like me care about it, but also to make sense of any alternative. That is, even if your thoughts and actions are not determined, and not controlled by God, why should you care? Even if God had not determined or even caused the Fall, why should you care? Even if he did not create you a sinner, why should you care? If he created you neutral, why should you care to choose to become righteous or unrighteous? Why should you care? If he created you righteous, why should you care to remain righteous? Why should you care? What, you would not want to become a sinner and suffer the consequences? But why? Why should you care?
If your thoughts and actions are not determined and caused by God, but are rather entirely produced by your own control and sovereignty over yourself, so that your thoughts and actions are free, and produce effects entirely attributed to your metaphysical power, so what? Unless you demonstrate why and how meaning, significance, and the reason for caring is established on the basis of indeterminism or human freedom, you still have not found any reason to care.
What kind of person does not care about God, and life, about truth, and worship, and loving others, even though God has issued many commandments about these things? What kind of person would spurn the divine commands because God is sovereign and man is not free, and because divine sovereignty is incompatible with human freedom? A wicked and worthless person.
Then, you say, “If God is sovereign why should he care either way? He is only getting what he wants.” Why should he care, because he gets what he wants?! How is this different from saying, “Why should God care? He is getting what he cares about”? Or, “Why should he want anything? He is getting what he wants.” Do you mean he should care only if he does not get what he cares about? Do you mean he should want something only if he does not get what he wants? Do you mean that to care and to want are by definition meaningless unless the care and the want are frustrated? If this is not what you mean, then what do you mean? Do you even know? If this is indeed what you mean, then why should I accept this premise? Or, is that just a careless and useless statement, and I am making too much out of it?
You are correct in saying that you are confused and that you need to repent. And I hope you are not being sarcastic about God granting repentance, because it is indeed he who grants or withholds it. Jesus says, “No one can come to me unless the Father who sent me draws him” (John 6:44). Paul writes, “Therefore God has mercy on whom he wants to have mercy, and he hardens whom he wants to harden,” and that we instruct people, “in the hope that God will grant them repentance leading them to a knowledge of the truth” (2 Timothy 2:25), implying that it is up to him to grant repentance, but that he might not grant it.
You will have to excuse me for being blunt, but I do care when people question the truth and appear to be sarcastic about it. If God has not granted you repentance to believe the gospel, or if you think he has but subsequent obstinacy against God’s word reveals that he in fact has not granted you repentance, then it means that you are still in your sin, and you will burn in hell when you die. But even if this is the case, you can take comfort in the fact that, since this has been determined by God, then although you will suffer extreme conscious torment for an endless duration in hell, you probably will not care.