If you think the energy you are absorbing is negative, the energy will be negative. Black in itself is not negative. It can be used to bring confusion to enemies in black magic, but the same black can be used for self-control (positive). What makes the difference when you cast a spell with the color black and whether that energy will be negative is the intention.
Intention manages Ki/Energy (see martial arts for example). If you put black energy with the intention to destroy, it will be negative. So if you absorb some black, with the intention of absorbing negativity, you are acting on the type of energy. Here "intention" is generic. Even a paranoia about something is intention about that thing is in that specific way. This is why once you perform a spell you should not keep thinking about it because your thinking affects it by still managing the energy even after the magic session.
From a psychological point of view, paranoia works through self-feeding. For example: Christians who learn they are fishing through thoughts. So they obsessively drive all kinds of "impure" thoughts out of their heads (study Christian obsessive compulsive disorder for more details), the effect they get is that this obsessive paranoia feeds itself and there will be more and more thoughts, etc. The Christian will recover from OCD only when he has abandoned the source of the disorder: the Christian's mental illness (I've been there).
No one here is having "sinful thoughts" because Christ is so irrelevant that we are not mentally disturbed. This digression was necessary to understand how these things work. Now, continuing to learn and wonder about on energy is becoming negative will continue to generate more paranoia. The solution is to do the meditation anyway without worrying about what our mind is making us worry with.
Anxieties of intention will disappear on their own like that. One very good thing you can do to help this even more is to look at a light source (not harmful to the eyes) and try to replay it in the visualization. This will make it better. As long as you don't spend too much time thinking about how to do it in the most correct way, etc., leave the left hemisphere alone in meditations.
However, do not fix the lamp. Just look at it three seconds and replay the image in the display. I have noticed that looking at it out of the corner of the eye works better than staring directly at it because the brain focuses more on an ideal concept of light (right hemisphere) than on the specific details of what the light looks like (left hemisphere).