medical question, bunch of SPOILERs

I believe at one point in the movie the Tim Robbins character "Mike" says that he gave his wife "hep C" and she forgave him. However, the research I've done suggests that Hepatitis C is virtually never spread through heterosexual sex, unprotected or not, except in freak occurrences where both partners bleed on each other. It requires blood to blood contact so the vast, vast majority of infections are spread through drug users sharing needles.

Since I was under the impression that the Tim Robbins character was addicted to alcohol and sex, (his character struck me as way too "high bottom" of an addict to have ever really done intravenous drugs) my question is, how did he give his wife Hepatitis C? Are we supposed to infer that it was a freak occurrence from having him having rough bloody sex with his wife after contracting it by another freak incident of rough bloody sex with another hepatitis c positive woman? Considering the chance of spreading Hep C during sex is about the same probability of impregnating someone with a condom on, this seems fairly hard to believe. Also, does this mean that both Tim Robbins and his wife are carrying the disease in the movie? They seem to only suggest that she has hepatitis c, but not him, which, again, doesn't make a whole lot of sense to me if he gave it to her.

Also, later in the film they accuse the son of stealing the mom's "pain pills" to which the son says something to the effect "oh, you mean the pills she needs for what you gave her?" which i assume is referring to the hepatitis c. How would pain pills (i assume they're supposed to be like vicodin or oxycotin or something) even help with hepatitis c?