In my opinion, she is not crying because she has never seen such beautiful shirts before instead it is because of Gatsby. She visits Gatsby’s mansion and is overwhelmed by seeing everything. Gatsby is rich and successful now and she wonders
whether marrying Tom was the right decision. I think that at that time, Daisy chose money over love and now she is regretting it. Since as, if she had married Gatsby, she would have ended up having both money and true love. She is crying because of her wrong decision that she has made in the past (about marrying Tom).
I think in the next episode of the book, Daisy will tell Tom about her past with Gatsby. Tom is an arrogant and short-tempered person. He is a rich person who cheats on his wife and I think he cannot bear/tolerate if someone cheats on him. So, in my opinion his reaction will be, either he will divorce Daisy or he will kill Daisy and maybe, Gatsby also.