How to deal with moving in/marriage/babies...and metamour?
My boyfriend of two years and I recently had a discussion regarding the future, and we would both like to head in to the living together/marriage/babies relationship zone, which is great. Our relationship with each other is awesome, as is my relationship with his son. (He is a single dad, and wanting to be sure about everything for his son's sake is the main reason why we aren't already living together at this point.)
My issue is my metamour, "Sue". I don't think this new situation will make her happy at all. Yes, I know, her feelings are not my responsibility- that was a huge stress relief to have figured out in this relationship, as she tends towards passive aggressive (and aggressive) behaviors that lead to major meltdowns. At this point, my feelings that her behavior is toxic to me and my relationship have been pretty much handled by my limiting time spent with her (not in a dramatic "I can't be around her way", just in a "I will be kind and pleasant when situations require us to be around each other, but I'm not spending unnecessary time with her") and by having our shared partner, "Joe", accept accountability for any of her negative behaviors being turned on me- once she realized that being nasty at me was not acceptable to him anymore, she started lashing out at him instead. If he wants to be with her and tolerate her personality issues, that is up to him- but her negative behaviors not interfering in our relationship are a requirement for me sticking around, and Joe knows it.
She has repeatedly said that if we were to "shack up", she would "die miserable and alone". She does identify as poly, although she has not dated anybody else since being with Joe. He is the ONLY relationship she has ever had and she is in her early 30s. I know Joe feels responsibility towards her particularly because of that, and because of her social awkwardness and introversion. She literally has no other friends but him. (I tried- but she was so nasty to me that I stopped.) I don't really understand why she feels that us moving in together would alter their relationship, particularly to that point. They currently see each other 1, maybe 2 nights a week, depending on circumstances. I actually recently worked out our schedule in a way that gives them more time together. I have already brought up with Joe that in our apt hunting, we should consider having our own bedrooms, so there is space and privacy for when they are together. (I don't love the idea of her being in my home on a regular basis, but it would also be Joe's home, and I'm capable of being in my own space or finding my own things to do outside of the home.) However, I don't really think it's a matter of anything I do- I think her own issues will cause some lashing out no matter what- and of course, Joe is going to be sitting there second guessing his choice of moving forward with me because of how negative her behavior will become. I don't even want to imagine her reaction to marriage and babies...
Has anybody been in a similar situation and can offer advice? Even without the negative behavior stuff, some practical moving in together while leaving space for poly advice is good too.