She sounds like my wife. Really messed up internally, about sex, and complicating it with alcohol and drugs.
Rape does that, compounded by the religious shame that is deeply imbedded around sex.
Sex with someone like a spouse is a trigger, for all the bad memories, and for shame, which makes sex at home a problem and usually messes up the marital sex life.
Drunken sex with another person does not have that effect, at least till the sobering up happens, which is when you are with the marital partner, and the self hatred kicks back in, which leads to the alcohol use and that leads to going back to the other person to try to prove that you are worth something to somebody.
Your wife is an alcoholic. She can never drink safely again, ever, in any amount, of any type of alcoholic beverage.
She needs to go to AA, and to go to AA hopefully with a womans group only, so she can learn about herself, not about alcohol.
She needs counseling, IC, not MC, she isn't ready for MC.
She SWEARS a condom was always used.
Never believe anything a practicing alcoholic says. You will learn that the hard way. They don't know what they have really done most of the time, and either deliberately lie, or confabulate up what they think happened, because they simply don't really know.
She did not use a condom. Get tested. She needs to get tested as well. Drunk people don't stop to use condoms, they don't insist on using them, they just don't. She probably doesn't even remember whether condoms were used or not, probably has no clue.
She used the alcohol to destroy her inhibitions and allow the physical act to happen.
No, she didn't.
Learn this about alcoholism, if nothing else.
Alcoholics use alcohol because they are alcoholics and they feel better when they drink, their bad thoughts and feelings go away, good thoughts and feelings come, and then they do things because they are intoxicated. This page below, which is an AA website, has a questionnaire from Johns Hopkins University that helps people understand their issues. It is very accurate.
http://www.lanarkleedsaa.org/pages/aboutaa/are_you_an_alcoholic.htm
Alcoholics have problems, and they drink, which leads to more serious problems, because of the drinking. It is a rare alcoholic that has not cheated on their loved ones.
You will find Al-Anon helpful, more helpful than you can realize, I know that I did.
I found all this out the hard way. I've been married to an alcoholic for 21 years, who has been in recovery for 3 years, and who I've never seen take more than 2 drinks at any time. However, she was a survivor of sex abuse, rape, and was a closet drinker almost our entire marriage. When she was having the affair, she would sometimes put away 2 bottles of wine, and cover it all up by telling me that she wasn't feeling good and would be asleep when I got home, and was driving drunk when she was with the other man. Only once she confessed to all the drinking, and the closet drinking, was she able to get the help she needed and make progress on dealing with her internalized shame around sex and relationships. In 21 years she had one affair, sex with him 9 times, in less than 2 months. But, in MC, she began to confess the rest, and was referred to other counseling as things came out about the teenage rape, her feelings, how she used drugs and alcohol to cover the feelings up, and how her guilt constantly drove at her like a flogging, and she felt better about the rapes if she had casual sex with random people, like it didn't matter so much that she had been raped if she did that....she confessed that she'd had so many sexual partners that she had no idea what the numbers were, but more likely than not it was over 200 before she met me.