I've seen middle aged addicts basically kill if not destroy their and significant other's lives. Have a friend who lost a sibling to illness more than likely was caused or amplified by their addict room mate taking rent money for their habit and forcing their 4th move in little over a decade. The proceeds from two houses and a businesses were dumped/used for their several trips to private rehab which was in addition to public or their own cash/health care plan trips. The last move which caused a great deal of hardship to the sibling fell to an illness in less than 2 years in which even the doctor could not believe how fast it progressed. Even at the funeral during a conversation some one mentioned some of their health/aches & pains and the addict offered one of their percosets.
Point being old habits are hard enough to break, an addictive habit or behavior is even harder. Especially to a selfish addict. If they had or given numerous chances to clean up/change I'd say you owe them nothing. Many addicts should be grateful for the first chance at redemption let alone multiple chances.
Good Luck