Don't attack the OM. The good news for you, is...well, he IS a low life right? Not some doctor who can take her away to Imaginarium where the sea is jello and all the food makes you lose weight...sorry MLC land for a sec.
Don't attack the OM verbally...DEFINATELY not physically.
Here is why.
You attack him, she defends him. She will. Sorry it sucks, you will drive her toward him. Its part of the beast.
If he is a low life she will discover THAT on her own. You attack him, you blind her she defends him longer. This si something where you can adversely affect what you want by doing what seems natural.
When you were first going out, she would defend you...sorry to say its the same thing.
You attack him, your the enemy, she will defend him.
Speaking from just a little experience here.
So have you determined what you can stand yet?
Experience is a brutal teacher, but you learn. My God, do you learn. - C.S. Lewis
Life is usually all about how you handle Plan B. - Jack3Beans
Listen without defending; Speak without offending - FaithinAK