My (f 29) bf (m 31) doesn’t see how problematic/toxic his friend group is.

My (f 29) boyfriend (m 31) has a large group of friends of many years. Recently, one man (m 33) was accused of sexually assaulting an acquaintance (f 28). At first, everyone was in agreement to cut ties, however this no longer seems to be the case. As a victim, I want my partner to stand his ground to the group and stand up for what is right. I do not want him to associate with people who are okay with this man’s behavior and instead want to sweep it under the rug. This has caused many issues between the two of us as he says he cannot control what others do and does not want to lose the rest of his friend group. Either way I lose: we stay together and he attends group functions where this man could be present, we fight, he doesn’t go, he resents me. How do I get through to him that the way his friends are handling this, or lack there of, is extremely problematic? Is there a future for us and how do we navigate if so?

TLDR; partner’s (m 31) friend accused of SA. Do not want partner to associate with people who are ok with this man’s behavior.