aita for not paying half the water bill?

I (19f) am a college student and live with 4 other roommates. I have had MANY issues with all of them since the beginning of the semester over petty things, but for anonymity, i won’t go into detail.

i invited my boyfriend over for a few days (he came over on a Wednesday night) since his work has been slow, and once the week ended, we were gonna head to our hometown like i normally do every weekend. he normally doesn’t come to my house at my university, especially not during the week, and i always go home for the weekend, ever since i first moved in in september. i think i’ve only stayed for 3 weekends since the beginning of the school year, and every break or day off of classes i usually go home.

Another important thing to know too is that over our winter break , 3 of my roommates and I all stayed at our parents house/hometown, other than one of my roommates. when we got back from break, the bills for utilities came in and since none of us were here other than one, we told her that we would pay the normal/base rate of all utilities and she would just cover the extra customer charges listed on the bills (only ended up being about $15 more). Long story short, our house broke into a massive fight for weeks.

okay now that you’re caught up, my boyfriend ended staying for 8 days in total (that’s including the night that he came over, so really only 7) I could tell after a few days that there was a shift in attitude in the house, so i asked one of my roommates if him being here was an issue, and if they had talked about it/knew if anyone else had an issue with it. she basically told me that none of them care that he’s been here, but they would be “annoyed if they had to pay the extra on the water bill”, so i told them that i wouldn’t mind paying an extra $15-$20 on the bill if i had to. Now normally, dividing it between 5 people, makes my portion around $30-$40, $50 max, and all seemed well after that.

Well 2 days ago i got sent a request for the bill. When I checked it in class, they had requested $108.

yes, i’m serious. from $35 (last month) to $108. I decided to ignore it for the time being, incase somehow it was an honest mistake, and a few hours later she cancelled the request. all is good right? she realized it was way too much. nope. 2 days later i got a request for $162 labeled water bill. I bet you’re wondering how much the bill was, right? $260.

I have had civil and polite conversations with them over text and in person about it, and how i refuse to charge my boyfriend $80 for our utilities for 8 days, and i refuse to pay more than half of the bill either.

am i the asshole?