Thank you all for your kind words.
I managed to avoid a major blowup, it wasn't easy, i just had to keep reminding myself that she is just looking for an outlet for her yucky emotions. Today she is much calmer, and said sorry for rambling on last night.
She is under a ton of stress, instead of trying to deal with it herself she has been dumping it on everyone around her.
Her son came out and was talking to her with me, she yelled at me because i hadn't said anything and her s said, if he talks you will yell at him more and if he doesn't say anything you will yell at him - coming from her son she took it better and changed her tune with me, too funny, if i said the same thing she would had flipped out on me.
I am happy with myself that i did not take the bait yesterday, i hope that i can keep up the same discipline in the future.