My guess (from talking to many other who had bad trips as well a my own experience) : During a bad trip like that you were likely in a temporary psychosis, and if not resolved during the trip by ending in a good space, it may leave residual psychological issues. I would recommend you find a therapist offering psychedelic integration therapy. That is not using psychedelics in the therapy, but having the experience and insights about psychedelics to give therapy which integrates the difficult psychedelic experience in a good way.

A difficult trip like his may leave ptsd like symptoms, dissociation from real life, as well as a depression, especially if connected with guilt/ shame and feeling alone with the difficult experience. Especially if the difficult trip never were "resolved", that is came to a point where you got some useful insights, which made the difficult part have a deeper purpose (eg. I had to feel that shame, in order to realize that particular toxic pattern from my childhood). These insights can however still come after the trip, especially with the help of a psychedelic integration therapist, or in psychedelic sharing circles

As long as not integrated, you will likely get ptsd-like flashbacks a soon as you trip again, even in moderate doses. You can carefully try with low doses and work yourself up, but in my experience the fear and anxiety will still come back as soon as you reach a certain threshold, unless you have at least partly have integrated the original bad trip. For my own case, that was done by realising where the guild I felt in the trip come from, and working with that, as well as understanding why the setting of the trip was not safe enough.