Hang in there, OP. These things are complicated and I'd encourage you not to take the judgment and derision ITT to heart, as lots of folks have been hurt by infidelity and take it too personally to have a levelheaded opinion on the subject. I'd also encourage you to ignore anyone who tries to gaslight you by telling you what your or even "Sarah's" feelings really are.
What you shouldn't ignore is the prevailing opinion that you need to let her go. That's solid advice, whatever the outcome. She's decided to prioritize working on her marriage over exploring her relationship with you, and even if you suspect she's feeling conflicted or unsure of that decision, she still needs time and space to figure out what she wants and what drew her to you in the first place. So do yourself a favor and refrain from reaching out to her. She may reach out to you someday; she may not. For your own sake, try not to hold a candle for her and move on with your life.
I don't want to give you false hope, but I've been in a similar situation and the outcome was a net positive. I was in a six-year relationship and caught feelings for a coworker who was married and had a small child at home. She felt the same and, like you, we ended up hanging out late after a work event and, once alone, our feelings came out. I broke up with my girlfriend a few nights later because I felt guilty and the fact that I was prepared to engage in an affair was the wake-up call I needed to come to terms with my dissatisfaction with the relationship. For my coworker, it was obviously much more complicated given her husband and child, and she did the right thing by coming forward to him about these feelings. I ended up taking a job elsewhere and took the hint when she immediately started ghosting me. Figured it was over and I'd lost my friend and someone I was in love with as well, only to have her reach out to me six months later to tell me that after months of couple's therapy she and her husband had decided to separate. We've been together over a year and a half now and just got engaged, I'm a big hit with her son, and, fortunately, she and her ex have a healthy co-parenting relationship.
Of course, I have to stress that such a happy outcome is a rarity and there are some pretty distinct differences in our situations: when my coworker and I realized we were catching feelings and having an "emotional affair," she ultimately refrained from starting up a physical affair with me, and was honest and open with her now ex-husband about the situation. She wanted to figure out the implications of our attraction for her marriage before rushing into anything, and give her ex a chance to step up (he didn't). This resulted in a foundation of trust for us that I would be more reluctant to give had she only come clean with her ex because of being caught.
That said, I'm glad to hear "Sarah" is working on and prioritizing her marriage right now. This a good and necessary step that you should respect and give distance regardless of the outcome. You don't want her to leave her husband for you and the excitement you bring to her life; you want her to give her marriage her all and only leave her husband because their marriage isn't working. This way, you can expect the same consideration in the unlikely event you end up together. For your own sake, consider that very unlikely. It will take a while for them to fix or give up on their marriage, and in that time you may have already moved on or feel differently about her. Whatever happens, I wish you luck as you grieve this relationship and can only say it will get easier with time.
