How does one survive this family drama?!?

My SIL (brother in laws wife...soon to be Ex) lives behind us (our houses are connected...the back use to be where the hay was kept and was turned into another house 10 years ago.) My MIL and FIL live in a little apartment on the first floor of our house for half the year and then fly back to their house in the winter...their like migrating birds, right?! We live in a cold climate making the outdoors very desirable living space during the warm months (3 months). Everyone is ALWAYS outside and makes for not so desirable conditions sometimes between family. We have talked much and hold family meetings to talk about any miscommunication or agreements/disagreements, 1X month. It helps A LOT!!! Glad for that. The situtaion is that my BIL had decided about 7 months ago that he was leaving to pursue music...and under the table also leaving his wife. My SIL has 3 horses, designer and deals her affairs from the house/farm. My BIL and SIL have always dealt a weird relationship...of seperate everything/money/living quarters...I owe you nothing/you owe me nothing...no favors and if so paid up with something right away. They've been married 15 years...until now. My BIL left and after 3 weeks fell in love with the woman he was roommates with. My SIL has researched the entire life/career of the new woman in my BIL life. I have had to pick up all the pieces my SIL and BIL have created in order to maintain the peace around here. Needless to say...its HARD to avoid this when she comes crying everyday the past 7 months whenever she feels like it (she'll call and make herself know by repeated door visits and calls unitl someone answers... 8 X's!!??) Because of it, she and my MIL and FIL are constantly walking on tippey toes never talking respectful, compionately, clear, or solution...NOTHING remotely peace keeping...there's always some DAMN: you parked in front of my window, you need too stop drilling...BLAH BLAH BLAH. DONE with this honest to god BULLSHIT. My MIL needs the meetings to make clear any issues. WHY???!!! Why can't you just solve **** along the way!! Be nice to eachother!!! This drama seems like its been forever between my SIL and MIL & FIL... decades. My BIL and my SIL will be meeting eachother at the end of the month and will decide how the house and living arrangements will be made. GOOD-I'M GLAD! But in the mean time what to do?!?!?!