very confused

Mary • My beliefs and opinions are constantly evolving
I saw on a post how a women got drunk and cheated on her husband and now she feels horrible about it and in the comments people are saying they don't feel bad for what she did.
Now I'm not supporting either side, but I for some reason was just confused?
There was a topic a long time ago and I remember people saying that if you're drunk, and you have sex with someone, then it's rape (if the other person isn't drunk). 
The lady didn't say much about the story, so I'm just going to assume that the guy wasn't drunk. I understand that drinking is not an excuse for cheating, but I'm just confused bc people have said many times before "drunk sex is rape" so I'm not sure what to think about these situations...
Not sure if it's controversial, so if it's isn't then I'll delete it, but what do you guys think about it, bc I'm not sure. Is it cheating or is it technically rape? 
Also if the lady who posted the story is reading this, if you want me to delete this post then I will!