Certainly 28 years was no mean feet. But I would never recommend anyone do what my mom did. Simply because ultimately it never served even the purpose she thought it would.
IMO if a husband and wife really have totally unsolvable and uncompromising problems that lasts far more time than it should, then it's better for them and their beloved off springs that they throw in the towel early than having to put themselves, their children and even other loved ones through the trauma of watching their constant bickering and obvious lack of love.
My mom, like a lot of women, will admit today that she was wrong in prolonging her marriage for as long as she did, and her final straw was her love for her grand children that made her decide to take the plunge. She says she didn't want her grand kids to go through the pain and suffering she believes her marriage to my dad brought her children, her mom and siblings and even her in laws and other relatives.
What children need more is a stable home of peace and love, and not necessarily will that be achieved by their biological parents being together without any love and peace between them!