I apologize in advance for the length, but there will be no TL;DR

Background context and characters: My sister “Bee” (24F) lives in Australia and has been struggling with a drug addiction for at least this entire year, if not longer. She is the only family member who lives in Australia, and everyone else is in our home country (across the world). She has finally come to the realization that she needs to come back to our home country, or she will be homeless. Right now she is living with a friend, but it is not a long term solution. She also does not have a job, so the only money that she has comes from social assistance. She is currently in the process of renewing her passport as it expired, so cannot come to our home country until that is done.

My mom (49F) does not have a job, so cannot provide any assistance to Bee in moving over besides advice and helping her fill out the passport application. My dad (55M) is the one who is going to be housing Bee when she comes over, and has sent money to Bee to cover certain expenses.

It should be noted that my parents have been divorced for about 20 years, and have not had much reason to be in contact until now. I am the oldest sibling (28F) and have been relaying messages between my parents (even though they have each others numbers), but I am getting sick of it.

Current problem: This last week my parents have finally been communicating without using me, but it has come to a head. My dad has apparently been bringing up mistakes my mom has (allegedly) made, which have nothing to do with getting Bee back to our home country. On top of that, he’s been very rude to her about these mistakes so she is fed up and does not want to deal with him anymore. My dad claims that my mom has done nothing to help Bee, and that she has blocked him for “some reason”. I am now being asked/am expected to again deal with the situation, as my mom seems to be bowing out. I am 8 months pregnant with my first baby, so this is not only annoying and stressful, but it is not my priority. At this point in my pregnancy, I want to be focusing on preparing myself, my husband, and our house for a new family member—not dealing with my drug addict sister, or listening to my dad rant about his ex wives and gf and how my sister should have come over when he offered in May.

While I feel for Bee and her situation, I don’t feel like it should be my responsibility to get her home. How do I explain to my parents that I will not be dealing with this situation, and that they need to learn how to act like adults and communicate respectfully?

The idea of telling them what I have written above is very tempting, but I know it will likely not go over well. My dad has a habit of sending long angry text messages without thinking of what he is saying, so will probably start texting me or trying to call me to rant at me. My mom will probably be so hurt she will start crying about how I hate her, and that I need to help my little sister so she doesn’t end up dead, and do you want that on your conscience?

Either way I feel is a lose/lose situation, but I just do not have the physical or mental energy to be dealing with my sister or my parents right now. I really need advice, please help lol.