There is a strong link between you being dissatisfied in your current relationship and seeking love and affirmation elsewhere. I believe you owe it to your family to do all you can to save your existing relationship. If it cannot be saved, then end it properly and move on.
Let's run with the idea of leaving your partner for the other woman. Imagine hurting your partner and kids and then finding that this other woman isn't your soulmate. Given that you haven't met this woman in person and haven't spent months together as a couple, it's far to early to be throwing around terms such as soulmate. At this point, all you have is infatuation. Yes, infatuation is overwhelming and feels magical, but the reality is that you can only truly tell if it's more than that after spending much time together.
I suggests you don't walk away from your existing relationship without both of you giving all you can to fix it. Cease contact with the other woman and get yourselves into marriage counselling. Your children deserve nothing less.
IF working on your relationship and counselling doesn't work, then end this relationship. When it's formally ended, you can be free to move on to whoever you want without regret.
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.