I worked 2 yrs in a Family Violence unit as a Detective back in the 90's. Couple things come to mind.. Someone had the idea of recording conversations. Excellent idea and in some states it is not illegal to record a conversation as long as the person recording is part of the conversation. Another thing is, anytime your spouse, GF/Fiance' starts beating themselves up, call the police yourself. It tends to make a difference as far as credibility if you call. Even if the psycho calls, never leave the scene entirely. Remove yourself from his/her immediate presence, but if you never talk to the police, they won't have your side. A warrant will be issued based on the physical evidence, his her form she fills out at the scene.
At this point, just sitting around wondering and waiting to see if the police show up is silly. You can call and find out if a report was made. You can ask for the number to the investigating Detective and you can give your side of it. It will not be the first time the detectives worked a case where the "victim" caused their own injuries.
If you are reading this from jail, disregard..