So you are married and you found your lost love? Uh oh. Maybe you are already in an affair and feeling torn? Who is the right person for you? You had/have a good marriage but now you are questioning? Did you make a mistake by letting your lost love go years ago, or not? Did you marry the right person? What will you do now? These are the issues I hear and address all the time.
First, let me say that you may feel torn because people can love more than one person:
There were many widows and widowers in my research project who, many years before, let their first sweethearts go and went on to have wonderful marriages; then, after their spouses died, they rediscovered each other and had happy second marriages. These were not people who thought they made a mistake, or longed for the lost love over the years; they chose their spouses wisely and loved them, nothing missing, but after death they discovered that old feelings can reignite again.
But note: they did not contact each other while they were married.
The mistake people are making, often without any romantic intent whatsoever, is in contacting their lost loves during their marriages. You can safely contact many old high school friends and enjoy these reconnections... but a lost love?... that's tricky.
If old emotions return, it does not mean the marriage is wrong. You may very well have chosen wisely when you married. But your new contact with your lost love has brought your past into the present and there was a collision, like a time machine that puts you in your teens and in 2012 simultaneously - that feels crazy, right? It's as if you are in an elevator and part of you is outside the door, part inside, and you feel squeezed.
Contact with the old flame brought you back to a former You, a different developmental period before you had so many responsibilities with work, children, home, extended family. Just you and your lost love... easy. Easy then, when you were young.
But it's no longer just you and your lost love. There is no real time machine. If you go with lost love, you are still a parent, still have to deal with the spouse you chose over your lost love years ago, and whatever people and issues the lost love brings with her/him.
The two of you are in a bigger context now than when you were young. But if you are in a secret affair, the affair hides the context, as if it were once again just you and lost love. Once you go public, there's that context: divorce adjustments; lost friends from your marriage, and new friends; (angry) ex-spouses to deal with, especially if you are co-parenting; lost love's children will become your stepchildren, and your children will become stepchildren, too; blended families, visitations, different parenting styles. This will not feel romantic, not the carefree lost love of the affair.
There were very few lost love divorces that surfaced in my research project, but these occurred because of blended family considerations, as in many second marriages.
You will also have geography to deal with (where will you and lost love live?); career changes and/or judgmental coworkers; financial losses; four sets of grandparents (and the two sets of parents of your ex-spouses will not be happy with you).
So, is your spouse wrong for you? How can you compare? A long-time marriage partner is the same every day, year after year. But contact with a lost love is new again, exciting, just like when you were young. The deck is stacked against the marriage if you are looking only at emotions of the moment. Affairs are exciting: anxiety creates the same hormones as sex, e.g. adrenaline, cortisol. Being a parent creates other, calmer hormones, as does the security of a long partnership and shared history. Each has its own rewards.
I am not saying that dissolving a marriage to be with a lost love cannot be worthwhile; only you can decide that. I just want you to look at the whole picture, to make an informed decision you will not regret. Look at the whole package that will be your future, after a divorce - the context - not just the current sexual pull of the lost love.
Maybe you did make the right decision, choose the right person to marry? Maybe you have just confused yourself by traveling in the time machine? It's worth stepping back to consider this, isn't it?