First I just want to thank everyone for their responses. Also I wanted to clarify a couple things I saw a lot in the comments.
1.) The apartment was originally Emily's and has her name on the lease. We've split rent and utilities since I've moved and have both agreed that we consider the apartment “ours”, but of course if there is a break up that means it will be me moving out.
2.) This visit from Laura isn't planned to happen til the winter now because of Covid-19, so Emily wasn't planning on having me leave in the middle of the pandemic.
So things have taken a weird turn.
This morning I confronted Emily about our conversation. I told her that I felt devalued and disrespected essentially being told to leave my own house for her friend. She apologized and said that she definitely did not expect me to actually be out of the house for a whole month. She had just gotten off the phone with Laura before we talked and was especially excited and just exaggerating. She then apologized again for just assuming that I would be fine with leaving our house and asked if I could try to maybe plan a camping trip around that time. I've always been fine with giving her and Laura some time to hang out one on one, and I'm a big outdoors guy who loves camping and hiking anyway so I agreed.
Ok cool, problem solved. I was feeling better about the situation, and felt like maybe I had taken things to seriously because I was somehow threatened by how close Emily and Laura are. I realized I maybe even felt a little jealous of Laura in a way, and so I wanted to tell Emily about it, clear it out of my mind and move on.
So a little while later I came back and told Emily something along the lines of “I think part of the reason I was upset is because I'm a little jealous of Laura and how excited you get to talk to her.” I explained that quarantine had maybe sucked some of the passion out of our relationship and that I missed that. She said that she loved me, that she understood what I meant about quarantine and that she wanted to try and spend some real quality time together. So far, great. Then she said, “But I get it, I mean I am in love with Laura.”
I'll spare you our debate about the nature of love, the gist of the situation is this:
Emily is in love with Laura ( yes in love, I checked), but considered it to be platonic because there is no sexual element for her. She said she and Laura think of each other as being soulmates and have since middle school. She also said that she had always imagined living together with Laura as an adult and hoped that the three of us could actually live together longer than we had originally planned.
After some more probing I decided that this seemed much more like romantic love than platonic love. Emily didn't really firmly deny it, she just said “well we're both straight, and I'm in love with you in a romantic way” or “I've never thought about it like that.”
Out of the frying pan into the fire. I'm very confused about how I even feel about any of this right now and I'm just trying to keep my distance and think things through. I'm upset, but also not? Part of me feels like if this had been clear from the beginning I might not mind necessarily, I see how happy Laura makes Emily and that makes me happy, and I like Laura too. Maybe I'm poly? But I'm definitely upset that this has been going on for so long. Everything just feels weird.