Might be worth it to get on a small dose of antipsychotics temporarily for the duration of the cleansing and strengthening process.
First of all - check for parasites and take appropiate steps to remove them. I won’t go on about that too much here, but there’s plenty of resources around parasites on the forum.
Secondly - strengthen yourself. Make yourself feel competent, strong, secure. Regular meditation, regular sleep and eating, excercise, especially stretching to release inner muscle and fascia tensions, meeting your needs, cleansing all serve to help with this. Doing things you enjoy, especially as part of sustained long-term projects is very valuable here as well. More concretely I can recommend Angelic Mantras, Angelic Mantras Redux according to your own propensities, as well as meditating on these words (they serve to strengthen your connection with yourself, deeper aspects of self and your higher self, because meditating on these continuously helps you iron out what these things mean and feel to you)
Thirdly - build trust. The most important is the trust you have for yourself, so that’s where you should start. Being consistent in holding up the commitments you make to yourself is particularly relevant here, but also achievement of things important to yourself, going through demanding situations successfully, keeping up the routine outlined in the previous step, being honest when introspecting and doing shadow work, consistent journaling and reflecting on what you have written. When you tryst yourself to be strong enough not to be taken apart by life and others, you cease having so many reasons to fear, thus neuroticism diminshes.
After you have a solid baseline of self-trust, the next, more perilous step, is to start taking chances with others. If you are magically competent and have some spirits you work with, depending on them a little may be easier than taking your chances with humans. But I suppose that depends on your disposition. Still, even if you are let down by others when you take a chance to trust them, if you have a solid baseline of self-trust already established, these experiences should still work to strengthen you, rather than make you fall apart. Just be careful not to overextend and overrely on others to a point where they could actually ruin yoir life.
Working on all these areas in conjunction (but also preserving the outlined priorities) should gradually lessen paranoia and generally make one more confident and stronger mentally.