What do you think about this ?

Part of being in a committed relationship is not putting yourself in situations where you might make bad choices. If you are concerned something will happen if you go drinking with your uni friend, then don't go drinking with him. Set yourself up for success and don't push your own limits, especially if alcohol is involved.

You aren't a bad person. Even married people are attracted to other people. It's what you do with those feelings that makes the difference.