Can't fall for him, right?

So how unethical is this? My friend and I are in a student organization at the top of the organization. My friend and I had previously dated but nothing came out of it (except for the occasional sexual encounter). Anyways, last semester he started dating this guy from the student organization and surprisingly I started dating his boyfriend's friend (who is also in the student organization). Skip it to this last weeks, I'm having relationship trouble (apparently I'm too unromantic and selfish) and my friend and his guy break up. This week I had a huge discussion with my boyfriend (almost broke up) and his friend (my friend's ex) starts scolding me about how I can't break up with him because of his depression. I retaliate by telling him about how breaking up with my friend left him (basically crying every day).Anyways this guy and I have been talking daily, to the point where we started comparing our love lifes and noticed that we have the same issue "we are too unemotional, work oriented and selfish". I feel like we have both kind of been flirting with each other, but it is completly inappropriate. He is my friend's ex and my boyfriend's friend... but I feel he understands me... Should I do something?