Husband on methadone

My husband has been on methadone maintenance for the last 10 years because of an addiction to prescription medication. He’s on a very high dose and he says it would be nearly impossible for him to get off it. He’s a good man but when he’s not working is either sleeping or sitting upright with his eyes closed. I’m really grateful that he isn’t taking pills anymore. It was nonstop chaos, lying and draining our bank account. It’s just that we have 2 kids and I feel like a single parent most days. Does anyone have any experience with this or know how difficult it might be for him to stop taking this?