That devastating moment

When you realize that you have the man you wanted. All you ever wanted was to have a good man and be his number one. His one and only.

That devastating moment when you realize that, thanks to making the mistake of a child with his now-ex-wife, you will never, ever, be his number one.

Do I stay? Or do I leave and let him keep that snotty nosed, mumbling, diaper wearing 3 year old and shut everyone out again?