I (28m) am thinking of divorcing my wife (29F) of 4 years.

Long read sorry

Some background. I met my wife in college when I was 18. It was like a RomCom when the main character lays eyes on the love interest for the first time.

I fell for her hard then and there. 2 months later, I asked her out, and she said yes, our relationship progressed to being married now.

While we were dating, I learned of her “sister” Kass. Kass had been her friend since she they were like 3 months old. Both of their moms are best friends that got pregnant with in about 2 months of each other.

At the time, her Kass was studying abroad and was out of the country. I knew about her, and my wife talked about her all the time. But, 2.5 years into our relationship is when I met her face to face for the first time. She immediately became one of my least favorite people. She is mean, judgemental, self-centered, and has a superiority complex (all my opinions). If the attention wasn't on her, she would make it about her. If you did something, she did it better or easier it was easier for her. I was nice to her and held my tongue, and kept my opinions to myself.

She was here for 2 weeks, then she had to go back. I noticed a change in my wife during those two weeks. She looked and acted like she was kass's personal servant and was just acting weird. I thought it was just her seeing her “sister” again after a long time. After she left, my wife went back to being herself again.

Kass was very vocal when I proposed to my wife about how wrong I was for her. How I wasn't good enough, the ring was small, the ring wasn't what she (Kass) would have wanted. She then made a social media post about me that she ended up deleting 30 min later (my wife told her to), but by that time, I saw it and saved it. It was disturbing.

We scheduled our wedding, and when we got about 3 months away, my wife postponed it due to “an issue with the venue.”” We got married 6 months later. Every time Kass is around, I don't recognize my wife. I have brought this up, but it always gets burshed aside, or im “ghost hunting,” jealous of my wife paying attention to anyone but me.

All of this led up to about a month ago. I used to ride a motorcycle everywhere. I was involved in an accident where a truck pulled out directly in front of me. (There was dash footage) I flew in the air, flipped several times, and ended up about 100 feet from the truck.

Injuries include. Grade 2 concussion, broken collar bone, and wrist. Dislocated shoulder, bruised ribs, and road rash on my arm. (I always have pants, a vest and helmet, so it could have been worse)

I am out of work for the time being, so I have plenty of time to think, listen, and watch. Kass moved back to the States last year and now lives an hour away. She came to stay with us while my wife was “going through a tough time.”

In the time she has been here (2 weeks) she has done nothing but complain and boss my wife around. She acts like she owns my house and everything in it. If I ask for any help, I get accused of being a misogynist, narcissistic womanizer by Kass. Every time I say something, tears start flowing, and I get told what a terrible husband I am. I can't have 2 seconds alone with my wife.

Also, in this time, I learned a few things.

She actively encourages my wife to go out with her and meet cute guys, go on double dates (without me), and more. (Wife always declines)

Kass has cheated on all of her past relationships and sees no problems with it. (She is a woman who deserves to be worshiped. But that just means she is easy)

Said marriage is barbaric in practice of a man owning a woman and suppressing a woman's natural need for multiple sexual partners.

At one point, my wife and her had exploratory relationships (before me and can confirm nothing since)

The tipping point for me. Our wedding wasn't postponed due to the venue. It was because of Kass. She didn't want our wedding to be a spring wedding. She “looked better in a fall setting,” and “the colors worked for her better anyway.”

I'm being ignored, disrespected, and talked down to in my own house. I don't know if it is the head injury, painkillers, or something else, but I'm about to say eff it and probably ruin 2 relationships in a hail word vomit.

How can I get the message to my wife that I can't stand Kass and that she needs to go. That the woman I love is not the woman I see in front of me. I want MY wife back, not this shell of a woman who doesn't see her own self-worth. I feel like a drastic measure has to be made for my voice to be heard.

How can I tell my wife I need her to be herself? How can I save the relationship? Is the relationship salvageable?

Tldr: wife's best friend is ruining my relationship with my wife. Nothing I say or do works. I'm always the bad guy.