Horse separation anxiety? Please help?

Okay, well I'm pretty sure the person that WAS boarding her horse at my house hates me now, anyway she came & took her hay & horse & left. My horse has been running & screaming for her for the last 35 minutes. He still has goats, & I'll be out there everyday with him, rain or shine. He's calmed down enough he'll take bites of his dinner before running around looking for his buddy. How long do you think this will last? Will he ever get over it? Tango & Penny have only known each other for a month. I don't know if he was ever alone before... I'm probably as anxious as he is worrying about him. Please, any ideas how to make is easier for him? I can't afford two horses, so please don't suggest that.