Addressing invitations question?

Ok, so how do you address an invitation to a non-married couple where the woman is divorced but still has the ex's last name? Let's say the last name is Smith.

Is it Mrs. Jane Smith and Mr. John Hancock??
or do you forego the Mrs. and Mr. and just put Jane Smith and John Hancock??

Thanks!

The outside is- (If they live together, if they don't live together they should each get their own invites)
Ms. Jane Smith (If she doesn't kids)
Mr. John Hancock
123 Somewhere Road
Dover, ST 12345

Mrs. Jane Smith (if she does have kids)
Mr. John Hancock
123 Somewhere Road
Dover, ST 12345

The inside would be 'Jane and John'