He is meeting the needs that your husband is not.
Your husband is also meeting certain basic needs (food, shelter, money) of yours that allow you to live in fantasy land with OM (other man) -- a land that is all about you, no pressures of everyday life, no bills, no fights, no cleaning, just fun. Plus having the secret is fun -- it makes you feel alive and daring. Like you're doing something just for you, spoiling yourself. It feels good. For now.
Guess what? When your husband is out of the picture, reality will settle in. Your fantasy land with OM is gone, you will have reality -- the reality that includes damaged children, divorce costs, lawyers, custody proceedings, a split home, bills, moving, etc. You will start to see a side of OM that wasn't present before -- he is now under pressure to meet all your needs, something that he didn't have to do before; something that he may not be capable of.
By the numbers, your relationship with OM will last about 6 months after your husband completely withdraws from the situation and ceases to meet any of your needs (money, shelter, food, etc.). You will likely move out of your home and in with OM, only to have it fall apart.
But right now, none of this matters, you will justify anything right now to meet your addiction; it is like a drug. You are looking for acceptance and approval, not reality.
You *could* try to patch up with your husband, clicking on the link in my sig would give you some insight. I know you're not interested though. You have to hit bottom first. Have a fun trip to Hell. Hope you make it back someday -- and I hope that your kids aren't irreprably screwed by the *only* people in the world that are responsible for their physical, mental and spiritual well-being. You know, they don't know how to take care of themselves -- that's what mommy and daddy are for.
Don't believe me? Do some reading over at the site about infidelity statistics and scenarios -- I'll bet you a hundred dollars you'll find a letter over there by somebody in almost your exact position... Hell, you can talk to other WS (wayward spouses) on the bulliten board over there (excellent resource).
Bottom line, what you are doing is not unique, what you are feeling is not unique. Nor is it real. What you are doing is based on deceit and false foundations. When it's exposed to the light of day and *real* pressures of everyday life, it will likely die. And then you'll have nothing. No chance at making the man you once loved back into the man you love, no respect from your children or peers (they won't say it to your face, but believe me, they'll talk about you behind your back), you'll have lost your house -- and probably most important, your dignity and self worth.
I expect your reaction to this to be inflammatory -- it has to to be as you *really* need to protect the illusion and falsehood you've created and cling to. And you will not take any of these words to heart, and you will probably not click on the link -- any of these things would be an acknowledgement that there *may* be some truth to the concepts I've presented -- and that can't be, right?
Again, have fun in Hell. Do your best not to take your children with you -- and try not to let your husband kill himself, after all, he's not the one having an affair.