I kinda think the problem might be that you don't feel the present moment intense enough and therefore have to rely on the past feelings which happen to be bad. 2 problems also: derealization in the present moment and bad feelings in the past possibly. solve one or both.
derealization, if it happens to be the case, can be solved with therapy or medication for example. depending on the underlaying cause by anxiolytics or antipsychotics or whatever. (or plain meditation and mindfulness. watch some Eckhardt Tolle videos on youtube!)
bad past memories can be resolved by therapy or self help books on PTSD or something. but I'd solve the derealization.
peace.
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Male
Aspie score: 131 of 200
NT score: 34 of 200
Possibly Aspie (diagnosed by an autism expert, doc moves abroad, forced to change docs and all say it's schizophrenia NOS or schizo-affective disorde or personality disorders. initial doc was a colleague of uncle Simon btw. you do the math.). (edit: by Uncle Simon I mean Simon Baron Cohen. Just to clear things up.)