<human>: Earlier in the year, I briefly dated a man who had recently gotten out of a serious relationship. We had a great time for the first month or so but, unbenownst to me, he got back together with his ex while we were still seeing each other. Rather than telling me that he wanted to be with her, he pushed me away until I decided to call it off with him. It wasn't until later that I found out they had been together and are now in a relationship again. That whole mess absolutely bothered me at the time, but I have since moved on and put the negative feelings behind me, and he and I are amicable (we run in the same circle of people and have to see each other quite often).

Jump forward to a few months later, a friend of his flies into town for the week for work. Please note: I didn't realize that they were friends, necessarily, but more like work associates. Well, we hit it off immediately and have since been talking every other day. I have a real crush on him as he's funny, smart and incredibly talented.

Now that I am getting to know him and realize that he and my "ex" are better friends than I had originally thought, I'm beginning to feel like I'm breaking some sort of code and feel these pangs of guilt. It seems like it's too early to bring it up to this new guy, but it also seems weird not to mention it at all. 

Oof... this is where I call on your help! I did not intend to develop feelings for him, but I have. Is this totally wrong? Any insight as to how I can broach the subject? Do I mention it to my ex, to the new guy... or not at all? Should I just call the whole thing off? Please be kind, but honest, in your wisdom.. thanks all!

Can you provide a brief rundown of the text in within 3 sentences?
<bot>: Ex's friend flies into town, and he and I hit it off right away. Feeling guilty for talking to an ex's friend and unsure about how to deal with it.