Hi Teresa!
Welcome to the recovery forum!
You said "I really need some help. I am in a situation that I don't think I can handle anymore. " Okay, read that sentence a couple of times. Do you see what's wrong with it from an alanon perspective? My hunch is that you did not misuse the word "handle" and that you have not really let go of the idea that there are things you can control about your husband. Step one is tough. You work it and you think you got it. Then you work some more steps and find out you have more work to do on one.
You asked how you could live with it if he killed someone in an auto accident. This seems to indicate that you would feel guilt and responsibility for the actions of another person. You are separate people. You can't live, act or recover for him and you can't assume his guilt either.
Addicts have relapses. Anons have relapses. For us that means descending into behavior that amounts to self torture.
Maybe you could tell your sponser you need to do step one again?
Keep Posting!
Smoke