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Don't be so rough on yourself. Opera is quite a topic to learn.
What I found useful in learning up on opera and in a way learning what I like, was to purchase the various Opera Highlights and Favorite Arias collections that so many labels offer. By doing this, I learned that it wasn't important that I did not understand the words ... it's about melody and emotion and passion. In fact, I find opera sung in english distracting. I prefer songs sung in italian and french ... I am still just so-so about operas sung in german.
With that said, some CD's to check out are (and there are others):
Placido Domingo "Verdi ... Arias and Duets" (EMI Greatest Artists series)
"O Mio Babbino Caro ... Famous Soprano Arias from Italian Opera" (Naxos)
"Operas Greatest Duets" (RCA Red Seal)
Ana Maria Martinez "Soprano Songs and Arias" (Naxos)
Giuseppe DiStefano "Operatic Recital" (Decca)
Regards, Rich