How would u react in my situation?

First, he shouldn't have been more of a priority than you're boyfriend. However, I would have told him "that you have no problem with them hanging out after all, you are the one who tried to get them together." He shouldn't have hid it from you, that was a big mistake on his part. Also remember, you're lady friend had just as much to do with it as he did. I mean after all, she hid the fact that they were hanging out from you as well. So if you're going to ignore one of them, you should ignore the other one too. But I see no point in that, it's not a big deal. Get you're friend back!! :) Hope this helps.