Go to an Addictions Therapist and discuss what's going on, they will help you move forward and deal with your husbands' issues in a way that will be helpful to him and necessary for you. They will have both of your best interests at heart. Absolutely, do not do nothing. Drug addiction is progressive, and before you know it your husband will be using iv drugs. That's the next progression fr him. (as it was for me an so many others).
There is a group for the families of addicts, called Alanon, or NarAnon, You can find meetings in person, or online. I think you should check it out for yourself. It will be suggested by the therapist, so if you have already checked it out, you'll be that much further ahead.
By doing nothing, you are enabling your husband, i'm afraid. It is not in his best interests to be enabled. Ground zero is when your husband is kept accountable for his actions in all areas of his life. Right now, he should not be left alone with the children. I would make sure that he knows that's starting now, if not already.
Do you have family and friends that you can talk to about this? Keeping secrets is not a good idea for either of you. it's best that this all comes out and is not being hidden from the light.
You say your husband has been an addict his entire life. Has he received any help for it ? has he been to rehab before ? or had an Addictions Therapist? Without any help , an addict is alone with his drugs. and his addiction. and the reasons why he became an addict in the first place. All of this can be dealt with for him with an Addictions Therapist. You've mentioned financial worries. Do you have insurance ? it might be that your insurance will only help him with an Addiction's Therapist if he's in a rehab, so it's a rehab that he needs.
Hope you stick around. You never need feel alone. There are so many that have been in both your husbands, and your shoes. We're here to help you both.
My husband and i got clean and sober in '99. and still going strong.