Primary Witness To A Murder At An Lgbtq Club I Worked At. Can I Sue The Convicted Defendant?

I was a primary witness to a murder at an LGBTQ nightclub in Sacramento California. The victim was a coworker and a friend. I was unable to save his life. I have been plagued with severe PTSD since. Ever since I have been in multiple treatments for this. I have spent thousands of dollars, gone through years and years of treatment, nightmares, flashbacks, my life was destroyed. The police department didn’t offer any support after the event. I was re-traumatized while testifying during the trial. What legal action can I take at this point? Can I sue? I have given up everything in my life and lost so much of my life.