Hi Glam, come on sweetie, you have put up with so so much and now this and yes plenty here would like to know why we couldn't have had a partner who would have been content with what they had and not go looking for the greener (or so they thought) grass.
You have no need to run away, go only if it is for the right reasons for you.

This is not DB but why would you care now.Why can you not confront him, show your anger and hurt, why still walk on eggshells for him after all he has done. I don't understand that at all.

He probably wont give you any answers but I am sure you will feel better, keeping it all inside is no good, sobbing in front of your daughter is no good either. He caused this mess let him see your pain.
If you don't want to see him tell him so, heck he,s never been reliable with you.
This is your time to take control of your life what you will and will not put up with any more. Don't follow your H with his rug sweeping tactics.
You need to get this out in the open, he has fathered a poor innocent child, this is who I feel sad for, certainly not your H.
Don't be ashamed Glam, we all make mistakes and you just picked the wrong man. Don't keep thinking of who he was, look at who he is now and who he has been for many years now.
Yes it is hard, but you have suvived so much up til now, find the strength,use your anger in a constuctive way. You have to let it out.

What does son say, I guess he knows,although I think this is son from previous marriage, try to stop wishing if only's, your h may never be that man again.
Take time for you Glam, take charge for you and your children.
I am so sorry it has come to this, but all things happen for a reason so they say. Without this news you could still be hanging on 3 years from now allowing his comings and goings and never getting any answers.
Thinking of you.