life too short to worry about "problems" of this level.
-Heavy chick-- just tell her flat out you're not interested. You're just wasting her time/feelings.
-sexfriend-- if she's willing to invest emotion/time/effort in you, consider being serious (if you can be). Otherwise keep it in pants until the fall.
Haruno Shiruba
There is so much not understood about the situation (by us readers, ie. I don't know enough)-- but from what is written, honestly dude I can understand Kevin and can't really get on your friend's side; though of course from your end, all you can do is try to support your bro, so I'll try to stick to advice that will be for YOU.
First off though, why I can't blame Kevin for being protective here. It's not just about thinking Bob will try to "steal" her from him. He's got to think about HER-- about her personal safety, both physically AND emotionally.
And her wanting to see Bob does not put Kevin in the wrong for stopping her either. Just like you can think Bob is a dumb ass and know better than he does what's good for him (and as a responsible friend, advise him accordingly), Kevin may see her meeting Bob as being bad for her despite her wanting to meet Bob. If he's worried about her, it's his RESPONSIBILITY as a good boyfriend to advise her against meeting Bob, and try to stop her (to the extent he can without using force or coercion).
This is especially unavoidable because Bob resorted to physical violence against Kevin-- him being unable to trust Bob with Viv's safety is unfortunately unavoidable. Or at least entirely justified.
If Viv is to meet Bob, she's got to really want it-- but the choice is her's alone, and there's not a whole lot Bob or you can do about it.
In any case, you guys should focus on Bob-- and for his sake, I'm not convinced whether meeting/not meeting Viv is even worth worrying about. Healing is gonna have to come from him, and he can't expect it to come from her. The more he worries and focuses on her, the more miserable he's likely to feel.
Honestly, I'm not worried about him studying abroad in Asia. As far as life paths /decisions go, they could be dumber. I mean, I have a friend who did the exact same thing-- studying abroad in Asia to get away from depression and a haunting girl issue-- and honestly he turned out much better for it.
When every simple task becomes a struggle with language and foreign culture-- eating, finding a toilet, not getting lost-- you're pretty much forced to get your head out of your ass. There's a lot of life lessons, a lot of self-discovery, and a lot of personal growth to be found abroad. Plus with all the pretty, foreign obsessed girls surrounding him, there'll be more pressing issues at hand (like keeping off the crazy white-obsessed psycho bitch ones).
I'd say using force on Kevin was the dumb decision here (amongst others), not so much the study abroad. Getting depressed, drinking, etc. was pretty dumb too-- but to me, it sounds more young than dumb. He sounds very young (and naive, and yes I'm saying this as one of the forum's older members based on the stats).
He doesn't sound like he's ready or in a state to get serious about life (studies, career)-- if he can broken up this bad by a girl, it's not like he's ready to face the "real world." So I'd say seeking out a change, seeking out a chance to grow up is good. Study abroad is not a bad outlet here-- getting lost can mean finding the way; as long as you got the time/money to blow on it.
Edit: Several years though? There is no reason to go soul searching for several years. He should cut his plans to 6months-1year, especially if he doesn't speak the language.
Try to be excited for and supportive of your bro, and get him looking ahead instead of behind.