Only Marina, I believe, and only at the hospital during the flashback. Other than that, the only indication we have that Marina knows that Elena is really Andrew is when she kept trying to use the 'earrings' code word. We didn't hear Sofia's side of the phone conversation, and Marina refers to him as "Aunt Elena" during that call.
Nikos has even gone as far to say he's never heard of Andrew Woods:
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Angeliki denied having met Andrew when he still looked like a man:
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The
one time Nikos seems to drop the act is when he says "this isn't a game anymore" and he wants to be with Elena forever, for real:
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This line doesn't make any sense if they've really been together for 30 years, as Nikos had been pretending up to that point.
Where are you getting that he met Aphrodite before? Because he says "I know you"? My best guess is that he's talking about the Elena character, not literally Aphrodite. We already know that he went to the salon with Angeliki after leaving the hospital, but we haven't seen that scene play out yet. My guess is that once the makeover is complete, he's going to see the complete character of Elena,
in the mirror, at the salon. This could very well be what drives him off the deep end, and could be the cause of the memory loss as well.