I can say that realization will feel like a curse for a really long fucking time. You'll actually mourn the old you that swept all those red flags aside and lived her life of oblivion... until you look at your kid(s) and realize you've been gifted the realization that you can pull them out of the tainted legacy of you and your husband's families. Because of your gift, they will have a much better, more fulfilled and enlightened lives than if you stayed. It won't always be so apparent, but they will truly be better off.
Mine always said "we will have to agree to disagree" about my feelings about his truly shitty behavior...real dick-wad, that one...as are they all.