How to pass a value from a Widget to a Catalog item variable

I have a custom widget which is pulling driving directions from a API and parsing it as a string to a variable. 

I can see that the directions are parsed correctly via console or system logs, however I now want to pass them to a text multi-line variable I have on the Catalog Item. I browsed the forums and saw some mentions of using $scope but nothing has seemed to work and I'm not familiar with AngularJS. 

What is the optimal and/or easiest way to pass this string from the widget to the catalog item variable?