It doesn't have to be all or nothing. Leave or stay. At least not right at this moment. If you are worried about something that may happen, the best thing to do is to make a plan in case it does. The saying "don't put all your eggs in one basket" comes to mind.
Don't put all your eggs in the sober-forever-husband basket. Hedge your bets and make sure you are prepared for the other outcome, should it come to pass. Having a plan B will also go a long way toward easing that tension you feel.
L