as someone who dates models all the time, do what i do cheat, get another gf somewhere else thats not too close to home, id say tell her to call around but never actually say your going out just let her think that idea.
Keep it as if shes a fuck buddy, then if anything ever goes wrong just dont call her if she asks why just say i didnt think we were serious, blah blah blah.
Models are models for a reason, they are for pleasure keep it that way.
Just say your fuckin getting back with her, keep your distance and i bet you can use her and abuse her as much as you want. Never let your feelings show, never tell her you want her to call, unless your drunk and wanna fuck, and never beg her for anything.
She will try harder than ever to please you then or dump you if you take it above the borderline. But either way she was your ex now, so youll not mind, get as much as you can before you split up if you do again.
give it a go its a monday you need some lol