I'm so sorry for your fear.
If there were something you could do, to stop his drinking, I'm sure you absolutely would be doing that right now. But there is not.
However, if he does call you and does speak of suicide, then call 911.
So many of us here tried so desperately in every way possible to make an alcoholic stop drinking, but we could not. Admitting our powerlessness over the alcoholic is the first and essential step to our recovery from the effects of alcoholism. And especially when we have children, we have to recover.
Sending a prayer to you today, for your entire family.