How about do everything in your power to protect your children. That will always be the right thing.
I'm totally confused about you not being 'allowed' to leave, forced to stay, but him being gone to get high, and asked to leave if he is? I don't get it. Are you locked in? If you are, and have access to a computer, do you have access to a phone?
Do you really want to expose your children to a 'wait n see' situation full of addiction, abuse, and potential violence?