How did Joe get so ugly in just a few years?

I think its supposed to represent how she saw herself in the times she was conveying in her recollections. The vivacious attractive magnet to men when she was care free and single was replaced by the world weary somewhat downtrodden and resentful person who is now recounting those times gone by. One has to remember that if these stories are actually true she would look at those good times through rose tinted spectacles including possibly her looks.
That's just my take on it though, but it could explain the rather sudden and dramatic ageing while those around her seemingly didn't. Perhaps she never was that stunningly beautiful young girl that she imagined.

The stupid have one thing in common. They alter the facts to fit their views not the other way!

Unless you have a portrait in the attic it happens to all of us.

I would not call her ugly. Shes just looks different from Charolotte. Theyre two different actresses afterall. For me, I don't think that they should have done such a drastic transformation in just 2 years after her son's birth, which was a bit insulting. First parents, especially mothers of 2 years old dont age that quickly. It also implies that childbirth destroys a womans look abd it doesnt. Also Im not really buying the symbolisn of it represent how unattrative she felt. The movie hadnt represented that much of symbolicism at that point. For me, I just think the placement of the transformation was wrong. They should have done it after she left her family because she started getting into a more rough lifestyle or kept the same actress or just some more years in there. For me the movie just fell apart at that point.