Me: 20F pansexual

Jess: 20F demisexual, mostly gay

Nate: 21M straight

Amy: 21F straight

Background: Nate and I met almost three years ago, were acquaintances/friends with benefits for the first year or so, and have been in a serious relationship for around 1.5 years. We've been poly the whole time - both of us realized poly was best for us before we met, actually. He doesn't experience any sort of jealousy at all. I get jealous, but only when I feel like my own needs aren't being met. I get mad compersion too. I've had many FWBs and gone on lots of dates while we've been together, but there have been less than 5 people I've actually really dated in that period of time. Since we met, Nate has only been involved with 3 other girls in any way - one he made out with at a party, and Amy, who he dated for about a month or two before she decided she couldn't handle poly, and Jess.

Jess joined our friend group maybe 2 years ago, but I never thought of her as more than a friend until this past summer. Jess and Amy were best friends, and Amy and Nate had been awkwardly flirting a lot, so Jess and I conspired to hook them up. She and I bonded over this, and I started developing feelings for her. She confessed that she'd always had a crush on Nate but thought he was way out of her league. Nate had previously told me he was passively interested in her, so I told her to go for it. She did, and everything was great. Nate was dating all three of us at once, and Jess and I were super flirty and physical (kissing, but no sex at that point). After Amy broke things off with Nate, we (Jess, Nate, and me) started hanging out alone together. We had a weekend getaway together and basically became a triad at that point. It was great! Nate and I both moved pretty fast emotionally with Jess, but we'd been friends for a long time, and she's a lovely person. Jess and I also spent a lot of time together, and had sex without Nate a few times, but all three of us have pretty low sex drives so that's not really a big thing.

In September, I suddenly developed a bunch of serious psychiatric problems. I have PTSD from being abused as a child, but hadn't really ever had symptoms except for anxiety before this. Suddenly, I was having severe anxiety issues, depressive episodes, suicidal urges, psychotic episodes, the whole shebang. Nate was and continues to be extraordinarily supportive. Jess has her own share of psychological baggage from childhood but has been working through it with therapy for a number of years (I haven't). She's very understanding and accepting, but she came to the conclusion that being in a romantic relationship with me was too stressful and triggering for her. I completely understand and respect that, but it still hurt. A lot. She and I "stayed friends" but quickly drifted apart, especially since my psychiatric issues lead me to isolate myself from most of my friends except for Nate. I was afraid that they would react the same way Jess did, by distancing themselves from me. I couldn't handle more rejection, so I preemptively shut them out (super unhealthy, I know). Jess and I have only seen each other a handful of times since October. Jess and Nate kept seeing each other, but not as often as before. My mental health is better now, but far from perfect.

Jess went to visit her family for 2 weeks over the holidays. The day she left town happened to be my birthday. Nate and I had plans to spend the night before my birthday together, and then the morning as well, and then he was going to help me prep for my birthday party that evening. When I pick him up at midnight (I worked late), he mentions that he's going to get lunch with Jess at noon the next day before her train leaves. Would normally be cool, but it was my birthday, we had plans, and I'd had a shitty day at work. I exploded at him and we fought for hours. He admitted he'd fucked up, apologized, and I forgave him because it was an honest fuckup - he's socially inept and didn't realize that was not the way to do things. He still went to lunch, because he didn't want to hurt both of us. I ended up sleeping until 2pm, so he was on his way back from lunch by the time I woke up. AFAIK, Jess has no idea this happened. Two months later, on her birthday, I had a really awful meeting that triggered a suicidal episode. I went to Nate for support and he tried to help me for about an hour, and then left to go to Jess's birthday dinner (which I was not invited to). I was upset he was leaving, but it didn't really have much to do with Jess, except for the added pain of not being invited to her dinner. Then about a week and a half after her birthday, she decides to have a birthday party with about 15 friends. She asked on Facebook which day she should do it, and it was pretty split but a few more votes for Friday. I commented "...but that's Valentine's Day :(" and she didn't respond. She had the party on Valentine's Day. I resented this more than I should have. She is quite socially savvy, so I'd be surprised if she didn't realize that I was less than thrilled about celebrating her birthday two weeks late on Valentine's Day and therefore being unable to spend it alone with Nate, but I'll give her the benefit of the doubt. I should have just talked to her about it, but I hadn't even seen her for 2 months before that, and it wasn't actually that big of a deal, so I let it go. I did shots before leaving for the party (I only drink once every few months, but I knew I was going to be unpleasant the whole time otherwise) and overall had a good time at the party, but had a massive depressive episode upon leaving alone. I called Nate and he walked me home, then went back to the party. I feel lost.

Oh, and Nate and Jess are both graduating from college in 4 months. I still have another 2 or 3 years to go. He's probably going to graduate school in a major city 350 miles away from our university, and she's moving to another city within 50 miles of that major city for a job. Nate and I are staying together even though we'll be long distance for at least 2 years - we'll be close enough to do weekend visits once or twice a month, and we were OK when he studied on the other side of the world for 4 months a while ago. I'm afraid that due to proximity, their relationship will become closer and more important to him than ours. And I don't want to be afraid of that. I want to be OK with it. I know I'll always be important to him, even if he has other equally important relationships... but I'm really insecure, I guess. :(

TLDR: My primary of about 2 years and I started dating another girl this summer, and she broke up with me (but not him) after about 3 months because she couldn't cope with my severe psychiatric problems. We don't see each other much anymore. I miss her and am sad we're no longer close, but have also started being weirdly jealous when my primary chooses her over me, even though he and I see each other almost every day and he sees her much less. I want to fix things but don't know how. I have discussed all of this with my primary and he hasn't really offered any input. Am I being unreasonable/needy/selfish here? How can I be a better partner and metamour?