Welcome back, LiLL, but I'm sorry that it is under these circumstances.
There is a difference between a slip and a relapse. However, I think that many people try and convince themselves and everyone around that they have "slipped" when in actual fact they were never really in recovery in the first place. Most alcoholics can white-knuckle it for weeks or even months. Was hubby getting any help for his alcoholism?
That said, I think threats of violence are beyond the pale. Do whatever you need to keep yourself safe. You are not a cold person for wanting to protect yourself and don't let anyone try and convince you otherwise.
If you are intent on saving your marriage, I would always suggest leaving for as long as it takes for the alcoholic to get, and stay, in recovery. Might be months, might be years. If your husband has a pattern of stopping and starting, then it would be sensible to see that this pattern has been broken before you go back.
Take care and let us know how you're getting on.