Op, before embarking on an affair, have a think about how your life will pan out once the affair has been discovered and you're heading in the direction of divorce. For one, the OM may not want to know once you're actually free, and you may find that being on your own wasn't all it's cracked up to be. But beyond that, think about this:
Imagine that your friends and family all know about the affair. It doesn't matter why it happened, the fact is it happened. Now imagine that they don't want any part in it, they don't want to know the reasons why, you are a liar and a cheat and that's all that counts. Your friends all side with your h, because he is the wronged party, at some point your children will find out, and they too may side with your h.
When it comes to starting new relationships, other men will think twice before looking at you, because you had an affair. They may not want to get involved with someone who has cheated before.
And then there is the separation. whatever an affair has convinced you of, don't kid yourself that walking away from your dh is going to be as easy as walking away from him into someone else's arms, or even off to be on your own. There will be heartache, recrimination, bitterness, and eventually your ex may well move on and another woman, over who you have no control will become a stepmother to your children. They may even have children together, and your DC will have siblings who you have no part in.
If you're ready for all that, and are sure that this man is worth all that and more, then carry on. But if, after you've thought about all of what I've just said above,then take a step back from the OM, and talk to your husband about where you want your marriage to go.
It's ok to leave a marriage because it has died or because it's become emotionless, but don't do it at the expense of your own integrity and self worth.