It would not necessarily follow that a husband would be duped by a wife having her tubes tied and stating she was pregnant, nor would he necessarily have to know that she'd had a hysterectomy.
But, he still could have been part of the crime.
Funny how we never hear this about the wives of male criminals. Maybe we should.
As for the husband not knowing about her tubal ligation, he wasn't her husband when she had it.
Finally, if Montgomery is 36 now and has 4 kids and had her tubes tied in 1990 (14 years ago) that means she had the 4 kids before she was 22 or 23.