Even if you're cut up, don't worry bro, you're human, you're supposed to. Everyone does. Obviously try to limit but don't fight it too hard.
If your mate was in this position and you could see a glimmer of upset, would you judge him? No. We've all been there, it's what happens.
General rule is as above, just try to ignore, although personally I'd probably fvck off, if I was not over her, why torture yourself? You don't get a prize.