Reducing reoffending is impossible - From Anon

Hello Prison Widow and blog readers.
I am struggling a lot with my thoughts and feelings concerning my partner of 11 years.
He is an addict and he is in prison because of it.
It's his second prison sentence and I have given him chance after chance. I visited him all the time when he was in prison the first time around but things haven't changed for the better. He is still using drugs and he is still making poor choices. I send him money which is supposed to be for telephone credit but I know in my heart it is being used for drugs.
I love him but when does enough become enough? He is released next year and he will still be a drug addict no matter how I dress it up and think life is wonderful with him. The bare truth is that I will be back to square one and day by day this whole prison thing is becoming exhausting.
If he is serious about coming off drugs then why is he lying saying he isn't using drugs in prison when quite clearly he is? His brother told me by the way because I have found out he has been asking him and his mum for money all the time. How can I support him to be a better person when he doesn't want to be a better person? How can I contribute to making him not reoffend again when he has a drug problem that I have no control whatsoever over? It is impossible.