He needs to find a doctor and start taking actual medications. Neither Ambien nor Xanax cure anything. Both are very addictive too. He needs antidepressants or mood stabilizers or whatever is appropriate for his condition.

Sharing meds is a very bad idea and illegal. I know love makes people irrational but you need to start thinking about this rationally. What you're doing is a downhill road to big trouble as yours and his conditions are likely to get worse.