You have to decide whether the guilt you feel is self imposed or imposed by a society that tells you how you should feel about manipulating others.
The thing with the LHP is, you get to set the boundaries of your own moral code. Contrary to the edge lords and psychopaths among us, being a black magician has nothing to do with being violent or psychotic, and everything to do with steering your own life. Personal responsibility is paramount, so you can still be what society calls a “good” person, caring about other people, and be a black magician, if you so choose to be. They are not mutually exclusive.
It is completely up to you to define what kind of person you want to be.
I suggest some period of introspection on your own morality, and the lines you choose not to cross. Get a picture of where you stand, and whether what you think is “right” is your choice for yourself, or society’s choice for you.
Once you have understood what is choice, and what is not, you can then decide to act in accordance with what is your choice of values. We only feel guilt when we act outside of the internal values we hold.
It might help to realise that everything we do when in the company of other people is a form of manipulation. Whether we dress to impress, or walk around with our head down and shoulders slumped, we are giving off subtle signals in order to manipulate the emotions and behaviour of others.