I'm sorry if I've missed this somewhere...
How long have you known him?
Did you meet him randomly in NYC and this is how it all started?
If this helps, I'll tell you about my situation.
I'm in an LDR with my GF. I'm in the UK, she's in California.
We met online last March.
We didn't meet in person until October last year.
Practically every day since we've met, we've spent about 4-8 hours a night on Skype, talking, video calls, texts, emails, the whole lot.
We actually feel we have a deeper relationship now, because most of it has been based around conversations on the phone.
We have an extremely deep level of trust.
Honestly... with your Brazilian guy... unless you are Skyping with him every night, it's going to be difficult to build trust.
You can't actually build anything unless time is put in. You also can't prove that he doesn't have a wife in Brazil.
STDs... well, I don't know so much about there being a bigger risk in people from other countries. It's probably more the case that more women sleep with foreign men, because of the romance of it all. So yes.. haha... he may have been around the block a few times... who knows?
The only way you can protect yourself from that is to use condoms and do not perform oral on him. Even if someone had shown me their test results, I still use condoms / no oral, until I trust them.
I definitely don't think you need to be ready to sleep with him next time he comes to visit. If he's coming for work anyway, then seeing you will be a bonus. Even if he's coming just to see you? You still don't have to do anything.
There is a chance that he could be genuine. I will admit that my girlfriend is ten years older than me and much bigger than anyone I've ever dated. But I think she's the most amazing woman I've ever met. It could be like that for him too.
I'll keep checking back on this question in case you add more details