Boyfriend Was Assaulted And Now It’s Being Turned On Him

hey everyone, my (24F) boyfriend (24M) was physically assaulted by his sister’s boyfriend (26M) a few months ago. My boyfriend filed charges, the assailant was arrested, we got a restraining order on him, my boyfriend got examined by a forensic nurse, etc. we have been going through the court process against him but there’s been no hearing yet. we just got something in the mail saying the assailant is now suing my boyfriend for assault even though he is the victim. the claims are completely false (i was a witness along with another person). we are applying to get him a public defender, but what else should we do right now????