If I were you, I'll tell the lady to move on and start fresh with a new relationship!
As you said, she now has a degree and self sufficient so obviously the previous life as a WL was to put herself through Uni, good on her.
But the writing is on the table , a former customer in general is Not a good partner for marriage in the best of times and you said it, if the guy is bringing up her past now, it will keep happening and ruin the marriage, call it off now before it's too late or when there are children involved !
Good luck