Tell her that it's not the end of the life. Life goes on and always changes. It's not a tragedy. But this person should remember all her mistakes and do not repeat it. There are so many divorces in the world! She is not alone.

She needs time to mourn her marriage. Just listen. If there were children involved then it will be harder for your friend. Make sure that she is eating properly and sometimes you may have to drag her out for a walk or to a cafe or the shops.

i think it's not quite possible to comfort her for a few words, words just don't work in this situation, a friend's accompany is just enough and listen quitely. long time marriage can leave lots of memory, bad and good, but it's good not to look back. find out what's going wrong wiht their marriage and accept what it is now. there's always a suitable person in the world waiting for you. he's just not the one.hope your friend get out of that situation soon.

君让臣死 臣不得不死， 天让其更新 其必须得更新。

Tell her "there are plenty more fish in the sea"!