Trauma related to unwanted physical touch by a relative – how to calm down the person ?

Trauma related to unwanted physical touch by a relative – how to calm down the person ?

So my gf had a bad mood yesterday, and she told me about how her own uncle tried to touch her while she was asleep, it happened a couple of years ago. She told me this yesterday, after 3 years of being in relationship together.

As it is the first relationship for both of us. I felt both sad and angry. But i didn’t know what to say to her.

She says she keep seeing that person’s face from that time again and again (he died he died 2 years ago)

I don’t know if i should post this here, sorry if i shouldn’t have. I just wanted to know how to calm her down and make her forget this incident

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TL;DR; : how to deal with trauma of your SO, how to calm them down and tell that everything is ok?