Wally and you were highschool sweethearts, until wally dropped out to pursue fortune randomly.

You at first worked as a phsycologist, but when the country fell into another depression, the only way to make money was selling drugs, robbing stores, or working for the 'welcome home mob'

The welcome home mob was run by wally darling, your ex. Since you didn't want any trouble you avoided him, only being a small medic for his mob, so he doesn't know you're working for him.