It can be done.

My husband and I dated in hs then after getting into trouble broke up for 6 years. During that time he got into trouble with meth.
By the time he and I got back together he had gotten clean. And my parents condition for allowing him back in their lives was he stay out of trouble. However, shortly after we got back together he started using and I along with him. 
We kept using together for 3 years till he got arrested. That was our moment of awakening. We have been sober for 3 years now. 
Some days are hard but it is possible. Love and dedication can conquer all.