Do you think she would choose him over me?

I have a friend that I developed feelings for. She and I are both single and in our 40s. This person is divorced and was involved in two separate and long term relationships that didn't work out. During those days, she lived in other parts of the country while my I never had a romantic relationship. During my life, I had female friends that I had a romantic interest in which never turned out in my favor. I am a virgin in my 40s. Although she and I never talked about us in the romantic sense, when we first started hanging out, she indicated that she wants to be careful about who she wants to be with the very next time. I am currently the closest male friend in her life at this time, and that means a lot to me. We both were going to get an apartment together due to our mutually long distance to work. Housing shortage around this area prevented that from happening. Anyway, I got myself a place and by coincidence she will be living in the same apartment building. We are both excited by this prospect. She's all I think about, but I do not want to appear clingly nor creepy about it. Anyway, there is this guy at work who is likable and nice. In fact, I generally have a good opinion of him, HOWEVER, he told me a few months ago he was attracted to her. She became friends with him recently, but they are not seeing each other (yet). I am worried, because she flirted with him twice. She's flirty in general and has flirted with me as well. During this past weekend, I had a house warming party. She invited him over and he hung out for awhile. We were the last three people at the party during the latter part of the evening. She snuggled up on him very briefly, and I was a bit hurt but hid my composure. We had some deep conversations at the end of the evening. She did give me kind words, and I was appreciative of that. It appears that she values what I have to say and my insights about things. But this person that is interested in her is also smart and better looking than me. Of course, just about anyone is better looking than me. I am concerned about this person stepping more and more into the picture. Do you think I have reason to be concerned? If they become an item, I plan to not show nor display any resentment about it. I won't personally be jumping for joy about it either. So tell me do I have reason to worry? Do you think she would choose him over me?