Hi summersover: Yes... emotions are SO complicated! I'm old enough, at this point, that affairs of the heart are no longer of much relevance to me personally.

But, when I was young, fidelity was not exactly my "long suit", as they say...

And I'm afraid I made some very bad choices along the way.

Some of them still haunt me to this day.
One thing that I wish I could have done, back then, was to view what I was doing from the perspective of: how will I feel about this when I'm looking back on it in 10, 20, or 30 years? Perhaps if I could have looked at it from that perspective, I would have made different choices... I don't know... But, at the time, I was so wrapped up in what was going on at the moment that I wreaked much of my own life & those of a number of other people as well... people who deserved infinitely better from me...
So perhaps there might be some value in your trying to visualize how you might think, later in life, about the choices you're making now.