I’m finding it so difficult to believe in black magic. If people can do black magic and have “unseen power” on each other then how is Allah in control? What’s the point of me trying to be successful when someone can stop me? What can I do? I feel stuck
Your question is like someone saying that if poison has the power to end life, then how is Allah in control or ‘what is the point of being good in the world?’ Another deeply false premise is the claim that anyone other than Allah might have power, which is not the case at all. That illusion is indeed from the sihr of dunya.
Allah has created means and properties in the things of this world and He observes and takes account of people over how they use them. Even so, the effectiveness of black magic is the flimsiest thing in the world and Allah has explicitly said that the wiles of the devil are ever weak (Nisa’ 4:76). Come to your senses and do your part in doing good so that you will be on the side of the Friends of Allah.