Does speaking about a traumatic experience help or make it worse ?

You have to find the right people to talk to. Find the people that genuinely care for you, and want to help you. After you've done this, talking about it, and hearing the opinions from your listeners can actually help. Listeners will generally try to think optimistically of your experience, and most of the times, they provide a different way of thinking that you have not considered beforehand. Therefore, their insights and thoughts may actually allow you to think in a whole new way, and can help you deal with your traumatic experience. Just remember, you don't have to fight a situation by yourself.

I would say there is always a personal way to react to facts and to seek for help, in case. Talking about it may be difficult, it may help or it may make it worse: suppose it also depends who we share that with, to feel that we can trust the person without being judged (but also feeling they are genuinely caring about how we feel emotionally) may play a key role. Probably for a sensible topic there is needed a sensible person too, no need to talk about something if we don't feel to but to have someone able to let us feel at ease in talking about a traumatic experience is probably a gift to be grateful for.