Okay, a little bit of backstory here.

My fiance and I have been engaged for about 3 weeks. He got me the most beautiful ring that is exactly what I have always wanted, and it fits me perfectly. The ONLY time I take my ring off is to apply lotion to my hands (I work in the medical field, which means lots of handwashing, sanitizing, and cleaning, so my hands get SUPER dry), and when I do that, I keep it directly in front of me on my desk and within sight at all times. I have never had any sort of issue until a couple days ago.

I have a coworker with whom I am friendly. Let's call her T. We used to be very close until I figured out that she and I lead very different lives, and I don't necessarily jive with her morals. Whatever, live and let live, I let a little bit of distance form between us. But we are still friendly and still talk at the office, so naturally I told her that I was engaged and she asked to see my ring. She oohed and ahhed at it like most other people in the office, and I didn't think much about it. But a couple of days ago, she approached my desk while I was putting lotion on my hands, with my ring laying directly in front of me as usual. Without asking, she reached down and picked up my ring and slipped it onto her own finger instead, holding it up and admiring it, etc.

I was flabbergasted. I didn't even know what to say, and I was so shocked that I just sat there in uncomfortable silence until she made a comment about how it looked so good on her and I commented "Don't go getting any ideas!", trying to be lighthearted but also wanting my ring back. She eventually took it off and handed it back to me and left. I was super uncomfortable with the whole thing, but I put it off thinking I was being too sensitive.

Today, I was walking past her desk and she asked to see my ring. I held out my hand for her to look at it, and she began to remove the ring from my finger, so I pulled my hand back. She got pouty and asked why she couldn't take it off and see it, since I had let her before. I told her I had NOT let her do that before, she had grabbed it without permission and put it on without even asking if I minded. She rolled her eyes at me and said I was being ridiculous. I feel like I am justified to be protective of a ring that represents my fiance's love for me.

AITA?

EDIT: Just to be clear, T is not gay, although it would in no way bother me if she was. She was married to a man (the father of her children) when I first met her and as I got to know her better I found out she had a lot of side guys while still married and still expecting her husband to take care of her. I was being intentionally vague about it before, because I didn't feel like it was relevant to the story, but since everyone seems very concerned, I'm happy to share why I began to distance from her.