Thank you both for taking the time to read and reply. I guess one thing that I am noticing as I read more of these forums is that I have yet to find someone in a similar situation as me. That's not to say I think I'm special or anything, and I know everyone's situation is different, but it seems that a common route to poly is having one partner, then falling in love with another one. This did happen to me, but I didn't know enough to understand what it was, and I did what everyone else thought I should do (leave for the new guy) instead of what I really wanted to do.
Now that I've been with the new guy for a while, and I am discovering poly, it is interesting to me that NRE has nothing to do with it. I just feel like I am finally able to say what I have known all this time: I am in love with two guys. I think this might help me "pitch my case" to the guy I am living with right now. The subject has come up in the past, so he knows I still love the other guy. He was pretty hurt though, and this is why I have hesitated for so long.
Since BU asked, my ex boyfriend would be much more likely to be in a poly relationship than my current. He introduced me to "open relationships" and values freedom, personal choice, being yourself etc. more than anyone I know, and he practices what he preaches. My current is pretty open minded, but also has a lot of anxiety and can be insecure, and hold a lot in. On the other hand, our lifestyle is very non-traditional in a lot of ways, so I'm not really sure how he will take this news, and if he will be honest with me. I am absolutely terrified to "come out" to him and I have no idea when a good time to do so would be.
This is very new territory for me. If nothing else, it feels good to be able to "say" this all out loud. I have felt like I have a huge secret that I can't tell anyone for a long time. It is definitely a good feeling to know I am not alone in all this.