I'm sensing a cry for help, here. You know this is 20 kinds of wrong, but you're so intoxicated by your fantasy luurve for OM that you can't think straight.
In my four months on SI I've seen countless threads where the WS said ILYBINILWY to the BS on his/her way out the door...and regretted it weeks or months later. Realized that once they have to actually *live* with the OP, the glow quickly fades.
What makes you think you're going to stop this...
making others happy while being so unhappy myself
...a change of address?
Consider for a moment that unless you figure out why you...
checking out of my marriage emotionally years ago and not giving my STBX a chance
...you may be doomed to repeat it.
Also think: how will you feel when your children walk down the aisle to get married, or get their high school diplomas? BH will be sitting there with his loving, classy second wife--someone by the time your 13-y.o. graduates college, he/she may be calling "Mom." Since, you know, she'll be living with your children instead of you. Great guys BH's age are a rare commodity and he won't last a year once he starts dating.
And where will you be in 10 years? Will your "soulmate" still be by your side? Remember, sweetie, cheaters cheat, and studies show only 10-25% of marriages started as affairs actually make it.
I am so sad reading your story. So sad that you're throwing it all away, and you don't even know it. So sad that your "happiness" will probably be short-lived, but could cost your children--and theirs--very dearly.
fWW: 42
BH: 52
DDay: April 21, 2013
Sweet DS & fierce DD, under 10
Former motto: "Fake it till ya make it." Now: "You can't win if you don't play."