It is human nature that when we want to do something that we know is wrong, we find justifications for it. In affairs, sometimes those justifications are to do with the concept of 'self-reward' for a difficult life e.g stressful job, sick child, brush with death, recognition of own mortality but when women have affairs, it's nearly always their own relationship that gets selected as the causal factor.
There are complex reasons for this. Women are socialised to nurture families and to associate sex with love, so when a woman has a sexual affair that could break two families, her guilt and the opproprium dished out by others is often far greater than it is for men. Because men are socialised very differently, they are often far clearer-sighted about the reasons for their affairs and their initial default is not to find causal factors in their relationship (although that sometimes comes later).
This is what I think is happening here with both of you. It's especially obvious on this thread because the grievances you have with your husbands are old ones, about situations where your own behaviour was complicit in the difficulties you faced. You are describing nothing new and in fact most relationships that were formed when a couple is young involve early immaturity and difficulty with responsibility. But you've both admitted that your husbands changed and grew up.
If your husbands were writing here, they might comment on their own frustrations with you both when your relationships were young, but they would be unlikely still to be holding it against you, unless it was suddenly politic for them to do so and was helping them to find a justification for doing something wrong to you both.
The solution is to own your true reasons for having or wanting an affair and to concentrate less on causal factors in your relationships and more on causal factors within yourselves as individuals. Don't let yourselves off the hook and acknowledge some things that might be unedifying about your own character and personalities, but nevertheless need to be faced.
If you don't do this, you will continue to blame anything and everyone for your own behaviour and some of your marital grievances will become self-fulfilling prophesies i.e. your marriages will become worse because of your interests elsewhere. This is why with some men, the 'causal factors' are re-written after the fact. Their marriages get worse because of what they are doing and there is some 'backdating' when this happens, rather than responsibility taken for causing the problems in the first place.
Women's reasons for having affairs are no different to men's. Some women (like some men) have affairs simply because there is the opportunity, they fancy the idea of having sex and romance with someone new, they like the attention and have a tendency to self-medicate when aspects of life get tough. The character traits are similar too; selfishness, an unwillingness to take personal responsibility and an over-reliance on romantic love and sex for own esteem. But women are far more likely to confuse lust with love (the former is still unacceptable for women, whereas the latter is understood and accepted) and because of the shame associated with women's sexuality, are far more likely to invent elaborate reasons for their behaviour that cast blame outwards and not inwards. Women in affairs are also far more likely to stop short of penetrative sex and delude themselves that they haven't been unfaithful, for the same 'shame' reasons.
What sometimes helps is to try to stand in all the other people's shoes.
How would you feel if your husbands were unearthing your initial relationship mistakes in order to justify an affair? How would you feel if some OW who'd convinced herself she had good reasons for having an affair with your husbands, felt entitled to do that without thinking of the effects on you? How would you have felt as children if your mother or father were causing this unhappiness?
The selfishness that is always involved in affairs often makes that difficult, but it's essential.