I also take an antipsychotic though for psychosis related to whichever schizo disorder I may have and that seemed to make the flashbacks go away as my psychiatrist said it would help. I say this after six months of them being absent although I still have invasive memories.
I suffer from PTSD. As for PTSD, a friend of mine told me to find humor in the traumatic event somehow if possible and it actually helped when I finally did and made it a bit more awkward feeling than traumatic. I laugh at "black humor" however, so it might not be possible for you if you don't share a similar sense of humor but I thought I'd share something that helped me.