Boyfriend drunk texted his female friend about his rape

I never knew my boyfriend was raped. Not until I read text messages he drunk texted between him and his female friend. He was talking about being raped at a party when he was 16. He went into horrible horrible details. Including the details of his rape kit and how he had a hard time healing. It was gruesome and she just get saying "I'm so sorry". He texted her a long paragraph today about how.sorry and drunk he was and to plz not share what he said to anyone. She said its okay and that he probably just really needed to get it off of his chest. I've been with him almost 2 years and if some female friend knows I feel I should know.. I want to bring this up and ask about it but idk what I would even say.