STI,
Ok, I'm going to put a bit of a different spin on this. I don't know your Mom, and I know that there are cultural differences in Hispanic families, even though I don't know what those differences are. But I figure that people are people.
Telling lies is a troublesome thing. The reason I say that is when you tell a lie, you have to tell more lies.
You should strongly consider sitting down and talking honestly, and privately, with your Mother. I have had to do this, and though it was frightening in the beginning, in the long run it turned out that it became the basis for a wonderful relationship with my mother.
S