Zoom is Jay? I think it's going to be more to it. I think he is either Hunter Zolomon from The Earth 1? Or he's a Jay from like Earth 3 or something?
The masked man believed Zoom was Jay and that's why he got so upset last episode. But at the end he looked completely shocked to see 2 Jay's. So he clearly thought Earth 2 Jay was Zoom and I don't think that's the case.
Now the question is whether or not the Jay we've come to know or not is good or an imposter? Before this episode I thought he was one and the masked guy in the cell was the real Jay. But know I do believe Jay is a good guy the masked guy is someone else and Zoom is probably Hunter Zolomon.