Lets get our feet under ourselves here and see what you can do for you. He is saying these things tonight, what happens tomorrow? You don't know. So I would suggest you do the following.
1. Demand the gun, get it and get rid of it. Take it to a friend or whatever, don't sell it, but get it out of the house, he is a danger to himself, you, the kids, OW and other people.
2. Lie to him if you have to, but tell him your willing to work on things if he meets on condition. That he checks himself into a full time intake facility. Not sure if is ready for a mental institute, alcohol program, whatever, but tell him you won't consider any kind of R unless he does this. Why do this? It will give you time to think, him time to change, and if it goes to D, which is likely, well now you have the huge upper hand for custody, home, assets, etc. Get the ball in your court.
Your such a strong person, I can't believe you did what you did and kept your cool as you did. What a story. Don't waste this opportunity to attempt to fix it, but don't waste the opportunity to do what is best for you and your kids. Get him checked in somewhere, NOW! Do it in the middle of the night if you have to, skip work, whatever, but get it done.
