If it's any consolation, I doubt if your stepdad is getting the free pass it may have sounded like at the time. A common pattern for people in your mother's position is to blame the victim in the first shock of denial, but to take a more balanced view when they've had time to cool down and think.

She's going to start asking her husband some nasty questions. "I was helplessly seduced" is not a dignified excuse for a man even if he's believed, and it doesn't carry a lot of weight in the 21st century.

As for your own husband, I may be wrong, but I get the feeling that you already had little commitment to that marriage emotionally, it just represented comfort and material security. You don't say if he beat you before, but you don't sound surprised at this one, so we are entitled to assume the worst. It's not unusual for people with submissive needs to mistake abusers for dominants, and it takes not only courage but clear understanding to break loose from that.

I've lost two lovers who chose to stay in unfufilling relationships for the house and the money, and I still feel sorry for them. You will look back on this as your day of liberation.