My Husband Has Been Diagnosed With COPD He Was Told

my husband has been diagnosed with COPD he was told that if he manages his health then it wont get worse is this true? is he going to die of lung disease? hes 40yrs old now smokes cigars still and weed what can I expect I understand his life expectancy can very I just want to know what to expect so im prepared and I think hes tryn to not keep me so informed so I don't panic but hes not realizing not knowing what to fully expect is making me worry more