I've carried the shame and guilt of it most of my time since then. However, upon meeting certain people whom I now count among my friends, I've learned to let that pain go and replace it with new found knowledge of myself:
I am polyamorous.
What does that mean? In laymen's terms, I may choose to take more than one lover. To those who lack understanding, it would appear as I'm trying to be a playboy; unchivalrous and uncaring for the feelings of my partner(s). This is, of course, furthest from the truth.
Should I choose to pursue more than one relationship, the first thing I do is talk to my partner. In contrast to 'cheating', polyamorous relationships are based on the same foundations as any other; communication and trust. Details are worked out, boundaries established, anything and everything that a typical relationship develops is no different. And now more than ever before, people are admitting to being in or desiring "open" relationships.
Finally, this should never be confused with polygamy. If I one day decide to settle down and marry, it will be with one partner and one partner only. Whether the relationship remains open will be a matter of discussion between my spouse and I.