Apologies in advance as this will be a long one — but need to properly explain the details to get some much-needed advice! I am not a mum yet but love mumsnet and can't think of anywhere better to get some impartial advice — totally ready to hear that I am BU.
So here is what happened: DP and I (both in our 20's) have lived for 3 years in a 3-bedroom house in a very sought-after area. We each have our own bedroom in the upstairs floor as I usually need to study and work well into the night and need my own space (I also often have family and friends overnight). On a different floor there is a completely independent room with a large terrace and an en-suite bathroom. Throughout the years we have always lived with friends renting that room and have always had a very fun, lively envoirement as we are not couple-y at all and enjoy sharing the flat. Recently, there were some huge probelems with the flat (ceilings etc) which meant a renovation was needed and our dear friend had to move out. Me and DP came to an agreement with our landlord and have carried out these renovations in exchange for a reduced rent. This means the contract is now under our name with a clause which allows subletting and we also have a very very good rent for a 3 bed flat in our area. Whilst we can afford the new rent just us two, we always thought of getting someone else to rent the downstairs room but were in no rush and were hoping a friend would move in a few months.
A few months ago, DP's brother got a job in our city and asked DP if he could move in. We were very happy and immediately said yes. Because he is family, we also agreed on a very low rent, so we shared with him our discount (which we got only through investing thousands in the flat) and gave up the really nice room and terrace as well as one of the bathrooms (the largest one in the flat). This was no issue at all and we were so happy to have him! We got on really well and had some great times. Fast forward around a month and he meets a girl, let's call her B. After going on a couple of dates it gets more serious and she comes over to spend the weekend as she lives in a different part of the country: she is lovely and we all get along. Obviously, she can stay over as much as she wants. One week after this, she gets a temporary job in town and asks if she can stay. DP's brother 'asks' by saying 'B will be staying for a couple of weeks, could be a month because of a job, I'm assuming that's okay?'. For us it was no problem at all since it was temporary. She moved in and started the job which lasted 5 weeks. After the 1st week they started officially dating and by the end of it, it became very clear that she had no intention of leaving and that she was looking for a permanent job in town. They never asked us if she could stay, but did say they would like to talk about rent. She said she didn't want to have the obligation to pay rent until she found a job. We should have seen the red flags (there were others, like requesting we don't use the living room one day so they could have a romantic breakfast) but we didn't and agreed she could pay no rent for another month and then start paying a very small amount (mostly bills) from the third month onwards until she found a job. The catch is she never found one (or really looked for one at all!). She wanted a job in a very hard to get into creative industry, but she has no experience and a degree from years ago (DP works in this industry) and she wouldn't take anything else. I offered to give her my babysitting contacs or put a word in for her in a café and she refused. She said she didn't want to take any part-time work until she found her dream job (keep in mind she has never worked in this industry after university and was working in a cafe before she moved in with us).
DP got fed up with everything and had a chat with his brother asking what she is doing and basically ended up blurting out that she was taking advantage of everyone. This is not how I would have gone about it and it was absolutely the wrong way to approach the subject but, in fairness, it was a brother to brother sort of comment. DP's brother immediately told B, who locked herself in her room and didn't come out for the rest of the day and night. I had a chat with DP and we called a flat meeting the next day in which DP profusely apologised to B, explained himself and all around made amends. We all agreed to move on, accept apologies and get along.
The problem is that ever since this happened they have been ignoring us, eat every meal in their room, come out of the room only when we are out... This is especially B as when she is away we all have dinner and have lovely times. This has made me so incredibly anxious in my own home and I feel a sense of dread everytime I go down the stairs to the common floor. I attempted a conversation and all she asked me was for details of when we will be away. They have also gone for a holiday and left their terrace door open (street facing) as well as kitchen knives outside which was so dangerous as we only caught it a couple days later and have left the kitchen very messy when we were away (we are both very clean and tidy but happy to compromise within reason, we never negged them and do most of the cleaning, we just ask that they clean up after themselves). I don't know what to do but we just want to kick them (or her) out! Especially as we never agreed to live with B! We just feel so unwelcome in our own home and this has really taken a toll on my wellbeing especially as I am studying for very important exams and finishing my dissertation alongside working. What should we do? Would really appreciate some advice as we ultimately don't want to cause any issues in the family.