Thank you for opening up, it was very brave of you to do so!

There's a whole lot to take in and unpack here, but I wanted to start with the fear of people leaving. My mom left me as a young child and I've had a really hard time with attachment my whole life as a result. In my early days of relationships, I would cling so hard that I ended up completely smothering relationships, or let them drag on far far longer than was healthy, simply out of terror being left behind. Once I got older, I swung to the other side of the spectrum, and stopped making connections at all, because it was just easier that way. To this day, I tend to shut down any feelings (platonic or otherwise) I might have for a person, simply because it's easier than the fear of being left behind, because all relationships eventually end, one way or another. But, I started seeking help for that. I tried to convince myself that my thinking was illogical, that there would always be someone to care for me, but that idea always fell flat. All evidence proves to the contrary. So, I've been working on a different method of healing. I'm trying to come to appreciate the value of a moment, however fleeting it may be. There is something precious about a moment - whether it last minutes or year - it's no small thing to choose to be with someone or spend time with someone or share a moment of vulnerability. I'm choosing to come to accept love in whatever form it takes, and let go of whatever notion of "forever" I've tried to impose on relationships in the past. I think those of us who have never seen a permanent relationship work out need to know that it's okay to let the experiences of life come and go in their own time, with their own purpose. It makes me feel better, anyway. To trust that each relationship has its time and its place, and what comes next will also have its time and its place. It's kind of nice to just not worry about the future at all, come what may.

Easier said than done, I know. Anyway...

In regards to your coworker, there's no easy answer. You have no way of knowing what the fallout will be. Truthfully, there's a good chance she's going to want to cut off the relationship entirely if you tell her the truth. Or, not. When I met my husband, I was already in a long-term relationship. It had been drawn out and unhappy for so long (for the reasons I mentioned above), that when this new person (who I adored) confessed feelings for me, it was like a miracle. A way out. But, if she is happy in her relationship, she may very well withdraw. Does the possible positive outcome outweigh the risk of the negative outcomes? If you are able to patient and the risk of losing the relationship entirely is too high, it may be worth it to wait and see what happens. Sometimes, these things have a way of coming out organically. Have you tried hanging out outside of work? That might be a good way to test the waters of how much of a distance she's holding between the two of you, depending on 1. if she's receptive to doing that and 2. what kind of setting/activity she's comfortable with. Heck, sometimes grabbing a drink together is all it takes for a person to start confessing their feelings (whether those feelings are for you or her current SO). Maybe the best course of action might be to just open the channels of communication wider, collect more information before taking any drastic action.

Good luck! <3