According to the artist who drew most of these issues, Jose Luis Duran, the Mexican publisher convinced Marvel to let them create their own Spider-Man comics by arguing that these were simply Peter Parker's dreams. After all, when a loved one dies it's normal to be haunted by dreams where they're still alive and have a much nicer butt. One issue even teased fans with the possibility of Peter marrying Gwen, though that turned out to be a dream sequence ... within the dream sequence (Gwen-ception?). It is also our duty to report that Aunt May is a total AILF in that issue.
This parallel timeline went on for 44 issues, with some U.S. stories thrown in between, and that was the last the world saw of Spider-Mex and the Bootylicious Spider-Gwen. At least until Into The Spider-Verse 2 comes out and takes place entirely in Earth-Mexico.