Dear girl, you cannot forfeit your life and the lives of your children waiting on him, to see what he will or will not do. Will he use? Is he hiding anything? What did he use? Will he go to rehab? What if he does? What if he doesn't?
That kind of anxiety will eat you alive and I think you have arrived at your "enough" point. Emotions waver greatly at times like this, you will feel the peace and relief of not having him using in your home. You will enjoy your children without wondering if they might find his drugs or see him use.
You can support yourself and your children. Please give them and yourself a life filled with love and peace and joy...yes, joy. When's the last time you felt real uplifting joy?
Perhaps you could sit down and make a plan for how you and your children will manage on your own, perhaps see a lawyer to find out your rights and what you can do to protect yourself and your children from his addiction or bad behaviour.
It will get better in time, it's a process, a painful process, to go through separation and divorce, but most times when a marriage is over it's like closing the door on an already empty room.
Hugs