I brought up my history because it's directly relevant to my point, not as emotional manipulation. Let me remind you of the comment I was addressing:
"I call anyone who admits to sexual assault a rapist".
Rape is sexual assault, but not all sexual assault is rape. I've had to discuss the technicalities of a rape charge with the prosecution legal team extensively (a gang rape in fact). I dealt with the police extensively. I gave evidence in court and was cross examined several times. One of our biggest hurdles was the jury, because people have misguided definitions of what constitutes sexual assault and rape. You ask me to imagine what it would feel like. I don't have to try, it has been over a decade and I still have uncontrollable flashbacks of it. If you're appealing to my emotional side on this I'm afraid I'm actually completely unreasonable in that I would literally kill the people involved given the chance. I'm not mentally well in this regard, however it does nothing to change the facts. My anger, your anger, and OP's anger do nothing to change what the legal definitions of rape are.
Maybe you think I was excusing the guy in the story. Is till think he's likely exaggerating because his claims sound far fetched. I've come across assholes like that, men tend to be loose with their tongue around other men. These people disgust me. That said, getting in between the mattress and springs? Bashing someone's head 100 times and they don't say anything? Doing it to multiple partners because "women don't complain because they don't want to make it awkward"? I think he's full of shit. That said, I think OP should tell her friend, and my advice was to couch her comments without hyperbole, because if she leads with accusing the boyfriend of being a rapist then I think her friend will dismiss the comments.
I'm sorry about what happened to you, but I don't think it helps victims of sexual abuse to have people running around saying things like "I define anyone who admits to sexual assault as a rapist". It's an uphill battle as it is. My case was a decade ago, and in my country what OP describes the boyfriend doing was not rape. I'm assuming OP is in the US. Court transcripts from some US rape trials are available online. A common hurdle for the prosecution is proving penetration by the defendant. In many cases the victim's head is covered by the perpetrators, or has their vision obscured in some way. Despite defendants admitting they were present during the attack this is not enough to achieve an actual rape conviction, at least in some states. Sorry but I'm not just throwing out random comments for the sake of it, I'm factually correct in everything I've said to the best of my knowledge.