I've read TFT, and this is how I see it, please correct me if I'm wrong:
You DH is addicted to drugs. Regardless of what type of drugs they are, he is a drug addict.
You are unwell, and have no financial support. By the sounds of it, you also have no emotional support. You sound like you at a very low point in your life, despite the additional emotional damage caused by your DH's addiction. Reading between the lines, I expect you also feel guilty at your inability to be with your children due to your illness, and want to keep them in a life as 'normal' as you can to minimise any further disruption or upset to their lives.
However, as previous posters have said, their lives are undoubtedly being affected by their current situation, and it is NOT FAIR on the children to be subjected to this. I know you care for them. I know you're worried about them. And I know you are at your lowest point right now.
But for this situation to change or improve, you need to take action. This situation is only going to get worse, and the impact on your children will be significantly greater. Posters have already said that if this is dealt with now, he may still be able to keep his job while seeking treatment.
No one can make you report him.
But you came on here because you know that it is causing damage to your family, otherwise you would have continued to quietly ignore what is happening.
Just speak to someone in RL. Just one person. Ring anonymously and tell them the full story.
Ultimately, this isn't about you, or your DH anymore. This is about your children, their welfare and happiness, and above everything else this is what you need to prioritise.