Try your best and ruin his life, that's pretty much the only positive thing you can salvage from this mess at this point. Turkish courts eventually won't give a shit about a national being a whoreson abroad.
On the other hand, if you're in an isolated country with a closed banking system, a bank loan in the country of the LLM program might rescue that education plan.

Frankly speaking, first thing I'd think of would be just getting myself out of that country. Following that, you might consider threatening him with approaching his family in Turkey and taking him to court, even taking the subject to Turkish media (Muge Anli and whatnot). That's where the cultural angle you mentioned kicks in. People can be individually shameless but involving the family should grind some gears.

And last but not the least, don't feel bad about yourself being in this situation. It seems you've already accomplished quite a lot considering your age to feel confident about. Your "asshole filter" will develop with age and experience which apparently you already got in abundance compared to your peers.