I had to decide what was most important and realized having a faithful and loving husband and father to my children was worth saving.

Counterpoint: It doesn't sound like OP's husband is being much of a father at all. He can't even be bothered to order a pizza for his daughter's birthday party! Not sure I'm seeing much worth saving in OP's case.

I also think it would be far more beneficial for OP's daughter to grow up with a strong, powerful, single (or remarried) mother figure than to grow up seeing an irresponsible father-in-name-only mooching off of her harried mom like a second child. The second scenario could very well lead OP's daughter to follow in her mom's footsteps by marrying a similarly irresponsible man-child.