Son went to marry and she left him at alter, he is now still talking to her, mom can't handle this

I can understand why the mother might not be able to handle this but there's nothing she could do. If the son is back talking to her, she can' stop him but only hopes he make the right decision in regards to his at least ex-fiancee. Also, all because they're talking doesn't mean their getting back together, it might be for closure.

Mom is being overprotective.
Also often when a son or daughter's choice in significant other is not up to mom's standards mom's will act like this. It really isn't good because mom needs to let her kids learn from their own mistakes. It is up to the son and his fiancé to work things out or not.
Leaving at the alter I can understand mom being upset but still she has to accept her sons
Choices or run the risk of alienating them. Often when the mother in law (or to be) is in the middle or taking sides she ends up being the one that is left out in the cold crying my son refuses to talk to me, won't allow me to see the grandchildren etc...
Keep the peace.

What were the reasons that she left him at the last minute? She may have had a reason to do what she did and if they were going to get married they must love each other. The mom may not know certain things about the relationship and that is why she doe not understand. The relationship is between the man and the woman... the mother needs to let the man be a man.