AIO because my girlfriend is blind to her family’s antics?

My girlfriend (32F) and I (30F) had her mother and brother stay with us for the weekend.

For context, her brother asked to stay for a family event happening in town, from Saturday to Tuesday. Then her mom asked to stay too, from Saturday to Monday morning. We agreed, even though our one-bedroom apartment is small. Her family is very close-knit, and while that’s outside my comfort zone, I was fine with it because I love them.

A few days before their arrival, her brother texted asking if a cousin could stay with us as well. I said absolutely not because we don’t have space. My girlfriend agreed, so I thought it was settled. But once they arrived, her brother kept asking over and over. Then at the event, the cousin told my girlfriend she had nowhere else to stay. My girlfriend still said no, but then her MOM started pressuring her, asking why the cousin couldn’t stay.

I asked my girlfriend why her family kept pushing our boundary. She said, “Just because they’re asking doesn’t mean they’re crossing it, and honestly, if it were just me, I wouldn’t mind her staying.” I was frustrated because we had agreed on this together, but it seemed it was all on me for calling out how rude they were being. Eventually, we talked it out and agreed her family was wrong to keep asking.

Then yesterday (Monday), I got home from work early so I texted her brother beforehand to let him know just as a courtesy that I’ll be home in 30 minutes. He said okay. 30 minutes later, as soon as I walked in, the apartment smelled like a Snoop Dogg concert. The weed was STRONG. And what makes it bad is that we live next door to the PROPERTY MANAGER, and her brother knows that. I opened the windows, turned on fans, and texted my girlfriend. I was LIVID. It felt soo disrespectful, especially since we had told him we only smoke outside or on the roof because of where our apartment is. Also, he knows that if someone gets caught with evidence of smoking, that’s an immediate termination of the lease. If I had not come home, we wouldn’t have an apartment right now!!!

When my girlfriend got home three hours later, she said herself that it still smelled like weed. She apologized to me and said she’d talk to him. But after she talked to him, she told me, “He said he wasn’t smoking inside, that he smoked earlier outside.” There’s no way that smell came from someone smoking hours ago outside. Then he lied and said I made it up.

Instead of backing me up, my girlfriend said, “Well, you’ve been uncomfortable all weekend, so I just won’t have them stay with us anymore.”

How is this on me???

I told her, “I wasn’t uncomfortable. I was MADE to feel uncomfortable by them ignoring boundaries and now lying on me!”

She kept saying I should talk to him, and I said I don’t care what he has to say. My issue is that there’s any doubt about what I’m telling her as her partner. She spent more time suggesting how I should handle it than addressing how disrespected I felt. I feel completely invalidated. She didn’t even tell him how I felt being put in that position, she was just like l told him “he has to be considerate because this is no longer just my apartment.”

I feel really disturbed in my spirit because I don’t appreciate being lied on, and I feel like her family can do no wrong in her eyes. Not to mention, the last time her brother was here, he had a party that was so loud, we got our first noise complaint EVER! Which says a lot because we’ve hosted many parties in this apartment. I want him gone, he leaves tonight and I cannot WAIT.

Am I overreacting??

TL;DR: My girlfriend’s mom and brother stayed with us for a family event in our small apartment. Her brother kept pressuring us to let their cousin stay too, even after we said no multiple times. Then, while staying with us, he smoked weed inside even though we live next to the property manager and had told him not to. He lied about it afterward, and instead of fully backing me up, my girlfriend seemed to doubt me and focused more on keeping the peace with her family. Now I feel disrespected and invalidated in my own home.