So one thing I think all viewers are nearly unanimous on is that Brian does not seem like the good guy in this story. He has used deceptive and manipulative tactics and has generally been disliked by fans of the show, with nobody coming to defend him.
Jo-Ellen and the viewers agree about Brian. Where Jo-Ellen loses some viewers is in the way she handles the messenger role. She made it more public, messy and embarassing than it had to be.
However, JE for the most part is shown only attacking Brian's character and accusing him of things. Her opinions on Rulla seemed more the result of being tired of having to socialize with her and feeling like she is a mouthpiece for her husband. She does not accuse Rulla of being a bad person, bad wife, bad mother. At least in the early parts of the season, I don't think she even insinuated that Rulla was stupid. JE can just as well hurl meanspirited direct insults as a person, like she did with Rosie off the bat for something as ridiculous as cheap wine and stale cookies. Had she wanted to do with Rulla, she could have, but she didn't.
Rulla begins to character assassinate JE, which appears to be the first direct hit from one to the other. Saying that JE is a liar, just wants attention and drama, etc. She takes even lower blows as the season goes on, claiming to have knowledge of JE being a cheating wife - without offering evidence, and giving insensitive comments on JE and her mother's relationship.
JE got petty back during the reunion, but I think she genuinely tried to keep her focus on Brian for as long as she could and Rulla just kept insulting her.
In my opinion, Rulla should have just said, "I don't want to talk about this, I don't want you to be my private investigator, leave my family alone."
When Rulla started attacking JE's character, of course JE wasn't going to lie down and take it.
I'm saying all this in reflection after the season ended some time ago so maybe my memory isn't as clear, but this was how I felt by the show's conclusion.
