I love Josh Duhamel and he would be such a great fit as well!
I don't wanna steal from whatever you're cooking up with ~bang, so no worries if you go in another direction. But the best friend could've been someone that she met at some point during her extensive schooling career (she was previously an obgyn), and that's also when she started to get into helping sell drugs - eventually the drug ring leader took her under his wing and now, long story short, she's running things. so either the best friend could've been someone she worked with in the medical field or they worked together with selling drugs ooor honestly, they could've met any way that fits your character - but bottom line, he'd be someone she could be fully herself around because right now she's living via an alias. i don't have as many thoughts on the ex line because it'd be something to brainstorm together.