I would wonder why he lied about it... like is he afraid to tell you for some reason? would you have been mad if you had known? I wouldn't get mad because it won't get you anywhere and it will only make him afraid to tell you things in the future.

Also, on the emotional infidelity, I don't know the whole details of your situation but sometimes it is better not to fess up to things like that, you know like why hurt your partner... I'm not saying not to be mad or that it's "ok" to have emotional affairs, I just think he could have a good reason other than just wanting to lie, and also does this mean it wasn't physical? I read a study about how men and women view infidelity differently, for men they are concerned solely about the physical sex act where as women are more hurt/threatened to think their man has fallen for someone else... again not that this makes his emotional affair ok or good, but if he didn't physically cheat at least it means in his man mind that he cared about you enough not to go there?