got assaulted by boyfriend friends while he was cheering them...

[fountainhall]

Peer groups and peer pressure are pretty strong in Thailand. So being made to feel good amongst his peers is important to many Thais, especially young ones. And let's face it, 19 is still pretty young and he will almost certainly be more tied to his peers/friends than to you. So take the advice given by others here. Ditch him right now. Violence has a nasty habit of repeating itself. You don't need that in your life.