תרגום - עברית-אנגלית - לא ידעתי שאתה בקטע של עובדים זרים

We've got more Hebrew slang here, which cannot be translated using a dictionary.

בקטע in this context is 'into':
I didn't know that you were into foreign workers.

Thanks Libers

And what does "into foreign workers" mean?

among them? considered as? or something else?

That's why in my previous translation I wrote: sector/section. But as Libera said that it is a slang Hebrew, I'll be glad if she can answer that.

How can I explain this - it's English slang.
The closest I can get is 'interested' in them, not academically, but on a personal level, as in wanting to meet them, mix with them. Or, like a guy would ask a girl if she was 'into him', interested in him on some emotional level.
It's not proper language, and can't really be translated into proper language.

Oh! Now I got it!

I thought the addressee was the foreigner...

So, that's correct.