I think that antipsychotic medication would be best in his case, as that usually kills sexual drive very effectively.If his libido is so fucking high that leads him to have severe mental and physical issues he should perhaps consider taking testosterone blockers or chemical castration... just saying, is as easy as that.
Messing with hormones can lead to even higher amounts of crazy and trooning out.
I do wonder if he has any history with meth abuse. It's not uncommon for methheads to beat their meat until it bleeds.