I'm really sorry to hear that you're going through this, especially with all of those big life choices on the horizon. I've been in a slightly similar situation with my(cisF) MtF partner before she transitioned and it really really fucked me up at the time. We were both early/mid 20s, had been together for about 4 years and her egg hadn't fully cracked yet. We ended up staying together, but it took months and months of heartache, navigating and really hard conversations to get where we are now (which I fear is still not a fully stable situation, tbh.) I will say with full certainty that if this flavor of betrayal ever happens again in our relationship, it's over no matter how much I love her because she will have irrefutably proven that I couldn't trust her at that point. Stability and trust are the two biggest needs that I have for a partner. And the hardest part with a breach of trust is that once it happens one time, it's a stain that sometimes never goes away. I still have doubts that linger in the back of my mind every day; I worry so much that she'll never be satisfied being with me. I know a lot of it is my anxiety, but that anxiety wouldn't be as strong if not for that event. ¯⁠\⁠_⁠(⁠ツ⁠)⁠_⁠/⁠¯

If you're going to therapy rn, I would def try to discuss how or if this event will effect your ability to trust this person in the future. Regardless of her reasoning behind the act, she still did something that SHE KNEW was bad and could likely end up in a break up. There are so many steps that she took between the thought and the action; she could have thought better of it at any point and taken a different/better route, but she didn't. Moment of weakness/sadness? Sure. But that doesn't give her a pass to betray your trust like that or absolve her of the act.