So I live in a house with roommates and my bf and most of us are in our 20s...however this 45 year old woman moved in last October and oh boy has it been triggering for both my bf and me. Now my bf only has untreated Adhd (that we know of, he's getting help) but he also grew up with a mother who steamrolled over his wants and needs, just like me. So this woman, who is our mothers' age, has been steamrolling our boundaries since the beginning. She asked if she could put some stuff in the garage, we said sure (cuz like what's the harm right?) Just leave us some room to work out...she left us a 6ft by 4 ft area to box/do weights. She took over the garage with her boxes and tools and now basically has her own woman cave there. We no longer work out. 
The common areas of the house that we are all paying for are now decorated with her stuff. She asked if she could get rid of the couches that belong to the landlord so she could bring in her own, I have 2 cats so I said no. I told her I can't keep my cats locked in a room just to avoid any damage to her furniture (the landlords couches are already old and wrecked so it doesn't matter what my cats do to them). But also, I told her we wouldn't feel comfortable having guests over (after Covid) bc the furniture would all be hers. She didn't like it but didn't bring it up again...until last night in her message.
She's moved my detergent from it's spot of 3 years and crammed 3 people's stuff into one cupboard just so she could have the other one to herself. 
She's basically treating it like it's her house, putting her shit everywhere and moving our stuff around to accommodate to her needs. 
Well yesterday, after a long day at work (I commute an hour each way) I get home and she's parked in the driveway. The understanding we've all had with previous roommates is that whomever rent there and had a car first, gets a slot on the driveway. So even if person A was living there first, but person C has a car and they don't, person C gets to park in the driveway. Now, I'm the first person to have lived there of them all and to have had a car, but I didn't make this unofficial rule. Our other roommate L did. And frankly, it kinda makes sense. So I politely drafted a message telling her about our unofficial rule and how I'd appreciate it if she'd just give me a heads up if she was gonna park there to clean her car, etc. At first she liked my message but then she sent me a long ass paragraph about how our landlord said that's not true and then basically saying " I pay rent, grow up". Our landlord has always been hands off, she lives 2 hours away and only talks to us to get rent and utilities every month. Unless something is really wrong with the house we don't involve her in our inner workings, because why would she care about some college kid's cleaning schedule or noise rules?
Now, I've started to fix my relationship with my mother so I sent her the messages and we talked about it and my mom reassured me I'm not crazy for wanting boundaries in a house I pay for to. She says I'm being more than sensible in my needs and wants (which like where was that when I was a kid?!) But I still feel like I'm the bad guy here. 
In her messages she bought up my saying no to decorations (which like all that's really missing is her couches and rugs) and how she pays rent so she should be able to do what she wants. And how she had to mop the other day and the floor was dirty which like yeah bitch, I'm the only one who ever mops around here so if I haven't done it in a few days it will be dirty! 
I'm sick and tired of going home and feeling that dread of seeing her. Of seeing what else she's changed in common areas while she plays house and tries to put us 'children' in our place. 
I'm questioning my sanity bc our roommate L has the master bedroom so they don't get involved bc it doesn't affect them as much and the other roommate K basically lives in his room and doesn't mind what she does. 
This was the first time I ever tried to put up a boundary and I ended up wanting to just cry to my mommy (who is like 50 percent of my abandonment issues). 
So now I'm crying in my car in my work parking lot waiting to talk to my therapist about the message I wrote back and re-edited a thousand times to see if it's appropriate to send. 
If you read all this. Sorry. If you're gonna be mean. Please don't. Also, I know my grammar is shit but I'm bawling my eyes out so cut me some slack.