My [27M] roommate [25F] told me that her long distance boyfriend will be staying with us, starting tomorrow, until they leave together in May. What do I do?

So I've posted on here about roommate issues in the past. Unreasonable cleaning standards, constant speakerphone use with long distance boyfriend. Same long distance boyfriend who visits and puts wear on or accidentally breaks my stuff.

Anyway, my roommate was cleaning tonight in the kitchen and says to me "oh, I'm not sure if I told you, but the reason that I'm cleaning is that BAAAAE is coming to visit tomorrow." Since he stayed 3 weeks last time, I immediately responded, "Oh. Uh, for how long?" She says, "well, for good, until we leave in May." (They're going back to where he's from for two months, before she comes back to finish out the lease for another two).

So, he's staying at least a MONTH. I was seething, but I tried not to blow up over it on the spot when she told me. I told her, measured and deliberately, that I wish she had told me sooner, and that's a pretty long time for a long-term guest. She sort of non-apologized and told me to feel free to tell her anything of our communal stuff that she doesn't want him to use, and to let them know anything they can do that would lessen the inconvenience. I told her it's really just having a third person in the apartment, and that's not something that can reasonably be worked around or lessened. My girlfriend comes to stay over sometimes for a night at a time, and I always give her notice. Last time, she responded "No need to ask booboo! Mi casa su casa (literally)." Which, like, makes no sense to me — it's common courtesy. Well, here we are. I had a feeling something like this was coming.

This is frankly unacceptable, and I'm frustrated because he's already coming. I'm pretty sure this was by design. She claims she's been so busy that she didn't even think to tell me, but that's obviously bullshit — I could imagine a world in which she was flippant enough about me to not bother telling me, for sure (I'm about 91% sure she's an undiagnosed narcissist, so it's possible she didn't even think of how it would affect me at all), but this seems more like a way of forcing my hand.

So, I'm afraid that keeping my cool made me seem more okay with this than I am. What can I do, and how do I broach this subject with her without making it as confrontational as I'd like to make it right now? Do I just deal with it and make myself scarce for the next month? Upside, no speakerphone to deal with? I'm kind of afraid that this won't be the last time: the plan, afaik, was for him to sublet a place in July and August before they move in together in September. What if she's like, oh, just kidding, he's "visiting" then, too? Am I justified in being like, this guy needs to pay rent, case closed? Is this a chat I need to have in person, or can I just send her a text tomorrow obliging with a list of things that are off limits for him to use, and also follow up with "and if he's moving in, I expect to split the rent this month 60-40?" If it were anyone else, I'd be ready to pull the lease up on her, but I work with her, and will be for the next 2+ years — so, I feel like I can't do anything drastic like get the landlord involved. We're in the same academic department, in which there's a pretty gossipy/petty culture, and we do work in the same subfield. We interact with the same faculty members. We'll have to travel to conferences together. I don't want this to follow me to work.

tl;dr my roommate's boyfriend is essentially moving in tomorrow, and I'm trying to figure out how to fight this while making myself the least amount of bonkers

Edit: I shared an update in a comment thread.

Submitted April 03, 2019 at 06:50PM by NotYourFathersEdits https://ift.tt/2CUgBzK