You've gotten great feedback here, so I'll confine my comments to the incident with the gun. I've worked in the DV field for a long time, and suicidality, abuse, and access to a gun, along with active alcoholism, are a lethal combination.
Along with everything else you are mulling over, I strongly suggest you contact your local women's shelter or the National DV hotline and talk with an advocate about safety concerns. Nobody will make you report anything or do anything you don't want to do or aren't ready to do, but they can help you get a realistic picture of any risks that you may face and offer safety planning and other suggestions that can help keep you safe during this period of time when things are in flux.
Hugs,