I'm getting married BUT have a BIG Dilemma..Please resolve. Thanks?

I am a 32 year old man hopefully getting married to a v nice girl in about 4 months. I have been diagnosed with Obsessive compulsive disorder and chronic depression and i have told my fiance all about that EXCEPT one important detail.. One of my psychiatrists told me that he can give me in writing that my marriage will end in divorce once the honeymoon is over (especially if i am not properly controlled with medicines and psychotherapy). Currently i believe that i am about 70-80% controlled (i dont think i can ever be 100% disease free). I have a reasonable job and I am taking the meds and psychotherapy. Should i be brutally honest and tell my fiance what my psychiatrist told me or should i be more diplomatic about it or hide it from her?