Hello,
I am not sure I can give advice, but I will try. I have quite a few male friends. We are having dinner together, we talk about everything and I really don't have any hidden agenda. My experience so far has been that the majority of these men would take more if I gave more. So in a way, it is playing with fire and if I had a boyfriend I would rip his head of if he had such a close relationship with a woman (just in case). At the same time, I find it annoying when some girlfriends get jealous at me. OK that's the general idea.
You say he "has no intentions of ever divorcing her. Because of this, I have tried to maintain a friendly association. Still, he emails me several times a day, telling me his schedule, etc." Sounds a bit like : I want to be with him, I feel bad about it (wife), I find legitimate reasons to be with him (one never knows: if he ends up divorcing, I will be around. Is his wife really interested ? After all, she left him alone with me !).
What do you think ? I am not saying you should let it be. As you said previously, it is better you know you are playing with fire and that you might get burnt. If you accept this risk, OK.
When it comes to love and frienship, should be always play it safe ? Are we kidding ourselves ?
I was once in a similar situation. I wrote the guy a long friendly letter. He probably thought I was crazy, but it helped me realize that I expected him to be much more than a friend and that I was expecting him to solve all my problems. After much reflection, I understood that while he was great buddy material, he was too easy-going with everybody (a pleaser) to be a good boyfriend. I also thought about his girlfriend and that was it. Today we are friends and I ignore any hint in another direction. But that's me.