They will work if you apply them correctly. Black magic is dangerous for inexperienced and novice people. If a person does not have the appropriate training, he can harm himself, just as people shoot themselves or not those they want when using firearms incorrectly.
You also have to make sure they deserve it. If so, there is no problem.
But I would think about how this will affect your natal chart in relation to relatives in future lives. These are not random people. I've seen a similar question before, I don't know the answer myself.
I do not know exactly what your problem is, but in addition to curses, there are binding spells, for example. If you see a negative for yourself in the long run from using the curse (and it may not be), you can apply it or something else.
To find out what magical works exist and how to make certain of them, take a look at the Satanic library. Approach this carefully so as not to harm yourself in any way.