Lol breathe please. It's just an AU version. And before someone says that this will be more important than comics, *minor MJ in Into the Spider-Verse spoiler*
spoilers:end of spoilers
...apparently at the start of the film, there is a moving scene where Ultimate Mary Jane delivers a eulogy at her husband Peter's funeral. So obviously they want just one MJ to split up with her husband. And that is probably to focus on how much of a failure Jake Johnson's Peter Parker is. Not a condemnation of MJ as a character, either on a whole or even just that one AU version.
Also, divorcing is not a scummy, immoral thing to do like you are making it out to be so relax.