1974cookie, as someone else said, smell is the most difficult sensory memory to eradicate. In 1976 trauma reactions were still misunderstood & dismissed, especially for by-standers. The specific trauma treatments for defusing such memories, such as EMDR, Eft & NLP rewind techniques, were not developed until the 1980s. When I learnt EMDR from the original developers it was not accepted & ridiculed by mainstream psychologists. Then there was a sudden change & it was often used as a quick fix cure all. All of these methods are very effective if used properly. I used to find the strongest memories were fuelled by previous experiences & fanned by future life events. I find people have to be ready to let go of the memories as they may be a useful reminder of something that makes sense of their history, even though their original use as a survival strategy is well past it's sell-by-date.
To answer your question, there is a lot on-line now your family & friends can read to help them understand. However, put the same person in the same trauma & they will all experience it differently. You might have experienced your trauma differently at another time in your life. It is a mix of the objective psychological facts of trauma with your own subjective experience of it. Many people are also very resistant to facing it too, even professionals.
When running training courses for people whose role was to give immediate help after a traumatic event, I was constantly horrified by how many complained if they were shown videos or given any kind of experiential training so they could learn how differently people respond in that situation. In the end I found it enough to get a group sitting comfortably then announce they had to change seats. That bought forth the whole range of trauma reactions including anger & botter complaints.
From the mid 1980s a lot of community outreach used to be done to reach people like you to provide information, support & self help ideas. Reactions like survivor guilt which meant people felt they didn't deserve help could also be addressed The medicalisation of trauma & focus on individual treatment of the most affected has meant these wider preventative approaches declined.
If your symptoms really get in the way of your life, do seek help though NHS waiting lists are long.
Forgive me if I've gone on a bit but this subject has been close to my heart for 30 yrs & I hate it when I hear people have suffered unnecessarily.