In lead:

• ...forced them to end their relationship because Pérez' image...-- Is there a convention that possesives for a name that ends with z uses apostrophes in this way?

In Relationship with Selena:

• This stressed Selena, who did not want to hide...-- Suggest a change to "This was stressful for Selena, who..."

• In 1998 he met Venessa Villanueva through his friend John Garza, and began dating her.--Not something discussed in any particular detail in the body; not closely related to majority of content on Pérez's relationship with Selena.
• Pérez and Villanueva had two children, Cassie and Noah, before divorcing in 2008-- Same as above; not sure present family life is necessary in the lead if it is not the basis for notability or more fleshed out in the body.

• Much of the early life and 1989—1995 sections are from an autobiography written by Pérez himself. I think the source is obviously helpful and ought to be used, but nearly half of the citations for this article are from the autobiography. Perhaps you could consider finding some independent sources that verify some (but not all) of these details, or perhaps cut some of it out? Obviously, the subject's early life is not why they are particularly notable (although, it is interesting to read).
• Under the 1999–2009 section -- The song was originally not planned for the album, for fear that listeners would think Pérez included the track for commercial reasons. -- is this sourced to Perez's book? If it is, the latter is little strangely stated. You might consider instead saying, "...for the album, as Perez feared that listened would think they included the track for commercial reasons."
• This line under Personality and musical influences -- Until the release of his book, Pérez had kept quiet about his personal life and shied away from media attention. -- has three citations, and probably only needs one or two.
• Some information under the 1995–1998 section, though more about Selena, is not clearly cited or does not seem to be from the court proceedings: When Selena arrived home she told Pérez that Saldivar did not give her the correct documents, and Saldivar tried convincing Selena to return to her motel room alone. Pérez told Selena it was too late, and he did not want her driving alone at night. Selena then agreed to meet with Saldivar the next morning. On March 31, she met with Saldivar, who delayed the transfer of papers by telling Selena she had been raped in Mexico. There is also the following sentence that I cannot verify with the sources present: Selena took Saldivar to a local hospital, where doctors found no evidence of rape.