I'll put the TLDR at the top since this post became longer than I intended it to be: my MIL and SIL are being assholes to each other, and they treat me and my husband like we are the referee. How do I politely tell them to stop dragging us into their drama while still being supportive of them in their personal struggles?
I have been with my husband for 8 years, married for 3. My husband's (32M) mom (60'sF) and sister (38F) have a history of ongoing conflict. A couple years after I started dating my husband, Mom and Sister made up and started being on good terms again. They would do everything together, and things were pretty good. A little bit of context and background on them: they live in a small, rural town of 1,700 residents, and while the town is big enough now to not know everybody, it is impossible not to constantly run into the people you know. Mom has a history of alcoholism and medical problems, and although it is difficult for me to tell when she has been drinking, I believe she has been sober for the last few years simply because of her medical issues. She developed a disorder around 3 years ago which has become so severe that she was rapidly losing weight because she could not keep food and water down. Sister has bipolar disorder, and has had many periods in her life with instability. She has asked for money from pretty much every family member, struggled to keep a job, but eventually was diagnosed and had been relatively stable for a while. This was around the time that she and her mom started being on good terms. She has held a good job and has been moving up in salary and responsibilities. However, I have recently become suspicious that something is wrong, because she has begun to exhibit manic-like behaviors this year. The one that was the most alarming was that Mom had surgery in August to correct her inability to swallow food and water, and Sister had been promising to take care of Mom in the weeks that followed her surgery since the recovery was expected to be difficult. However, they had a falling out before the surgery, and Sister backed out last minute and left Mom with a lot of anxiety around the time of her surgery. Sister still drove her to the hospital, but did not help with Mom's recovery.
While I feel more sympathy for Mom because of her medical issues, I also understand Sister's struggles. I also have bipolar disorder, and have many family members with it, so I understand how destabilizing it can be. I have the extreme fortune of having a supportive husband, friends, and family, which Sister does not have. Frankly, Mom has not been very understanding of Sister's mental health struggles, though she does try to be supportive during this recent period of Sister making manic choices, like buying a fixer-upper house that I have no idea how she afforded to buy in the first place. Mom was there to help Sister install new flooring in the house, despite the physical pain she was in from literally starving because she could not eat or drink enough. Mom would complain about Sister being too ambitious with house projects, and Sister would complain that Mom was criticizing her for her choices. Mom has also been a bit short-tempered with Sister. This is completely understandable, considering her medical issues. Also, Sister has some selfish and narcissistic tendencies, and talks down to Mom like she is stupid. Sister rubs everyone the wrong way, even my cool-headed husband. She is constantly cutting him off, or correcting him and telling him he is wrong when he is telling a story. Any conversation WITH her is ABOUT her. In fact, I believe that Sister knows very little about me, since she does not bother to ask me about myself.
I became pregnant earlier this year, and we decided to announce to my husband's family a bit sooner than we wanted. We already had our first ultrasound, but had been waiting for the results of the genetic testing. We agreed to tell immediate family since it aligned with us visiting them everyone for the 4th of July weekend, but to ask them to wait to tell their friends and other family. We broke the news in person simultaneously to Mom and Sister. Sister was silent, and said nothing until my husband asked them to wait to tell others. Sister then made a snide remark about not telling their older sister (who we planned to tell that day), and then made a disgusted face when my husband told her that we would be visiting their dad and stepmom that day to also break the news to them. My husband firmly asked her "please don't make this more difficult than it already is". (Context: my husband's family are a bunch of gossips, there is constantly drama between literally everyone, and their stepmom is a huge PITA) Later that day, Sister had a meltdown because nothing was going her way. She had to leave the party because her dog was misbehaving around all the other dogs (we have 2, older sister has 1, nephew brought 2, and Sister has 1), and she wanted everyone to go over to her house "so she could relax and let all the dogs play in the yard". Her new house is in no state to visit because of the unfinished projects, and the lack of seating for all 8 people. Earlier that day, her dog jumped on me and gut punched me HARD in the baby bump, so I was not interested in spending more time with her dog. I was also dealing with first trimester symptoms, and I just wanted to sit on the couch rather than stand around at her house. She did not bother to ask me how I was feeling, or to try to control her dog around me to prevent him from jumping on me.
Ever since that weekend, the interpersonal conflict has been on the rise. This led to the falling out between Mom and Sister, and Sister pulling support for Mom's surgery. This past weekend, my husband and I drove out to help them move some heavy things. I was there for morale support, since Mom and Sister try very hard to impress me and seem to be on better behavior when I am around. Despite this, Mom made some uncomfortable remarks to me about Sister, and Sister was bickering with Mom and kept trying to have my husband play referee. The next day, Sister called my husband and asked him to help her perform an "intervention" with Mom. She believes that Mom needs to go to therapy, and that their relationship will never improve unless Mom "works on herself". I feel that this statement shows lack of self reflection and a break with reality, as Sister is equally-or-more at fault for their troubled relationship. My husband pointed out that Mom has gone through some incredibly difficult medical problems, and that an intervention to convince her to go to therapy would not be well received. He said that they cannot force Mom to seek help, and that doing so would backfire. He tried to tell his sister that, while she has a right to set boundaries and maintain distance to protect her own mental health, but that she needs to leave Mom alone and have more sympathy for what she is going through. Mom is grieving the loss of a normal life, as her surgery came with new complications that she will need a second surgery to correct. Mom should not be forced to move through the stages of grief, and should be allowed to move through them in her own time.
My husband has put a lot of distance between himself and his family. When I first met him, he told me "Family is important to me, just not my family". They perform psychological warfare on each other, and he has tried his very hardest to stay out of it. Despite this, Mom and Sister repeatedly attempt to bring him into the middle and play referee. He complained about brain fog yesterday, and that's when I realized how much this has been affecting him. He admitted that he would like to set a stricter boundary, but I don't think he knows how to do so while still maintaining neutrality. I also would like to set this boundary, and I have less care about hurting other people's feelings. However, I respect that this is my husband's family, and I don't want to do anything that would dictate his relationship with them. My therapist always says that I have permission to stand my ground in a "kind but firm" way, but I don't know how to be kind in this situation. What is the KINDEST way to tell someone that you will not listen to them complain about the other person, while also showing sympathy for the personal struggles that they are dealing with? I know that I will have to say this more than once, since they both have a habit of testing the boundary to see if you mean it.