I was a victim of an assault and injured my attacker, why was I arrested without being examined first

My boyfriend assaulted me and I injured him in self defense, I called 911. When the police arrived they escorted me down stairs, searched me, cuffed me, placed me in the car and began to question me. I was injured and was never examined, never read my rights, and had to be bailed out to try and keep my job. I was cooperative and forthcoming about the incident even though I was traumatized by the assault. I took myself to the er after bailing out, the doctor examined me and determined that the injuries I sustained were similar to being in a severe car accident. Three days after the incident I was interviewed by the detective. Ultimately the DA rejected the file, but as the victim of the assault I’m still dealing with all the repercussions of the attacker. I don’t believe this was handled properly, am I wrong?