Why would my mother complain about my father, only to then tell me to mind my own business?

The only thing I ever did was tell that truth:

She's disgusted by my father and that she's miserable staying by his side. That's how she's been feeling for many years already, complaining to me for the longest. My father isn't a Saint either. Both stayed in a rocky, unhappy, unloving marriage for too long (long overdue)... it's pathetic.

Obviously this created another argument and now she claims I ruined it all for her (yeah she's upset my father isn't going to give her money for her trip she scheduled with her female friends), that their arguments is none of my business, to stay out of it.

I thought I was providing the best solution: let it all out and free her, let her be happy again so she can't complaining to me.

Updates
+1 y
The solution obviously is to separate if you're so miserable. Obviously she's too much of a coward to do that. She's focusing on what will her family members, friends and others will say, oh what will they say. Screw that.
Why would my mother complain about my father, only to then tell me to mind my own business?
Post Opinion