I've been in the same situation for the most part... where reality and what other people thought or heard were completely different. I think your mother is 99% right. Take the high road. But... be prepared with a response that will leave them wondering about THEIR perception of things. If ANY of his friends have the nerve to approach you in public to tell you anything about YOU AND YOUR MARRIAGE, don't fight, don't argue, don't defend yourself. If you do, you prove him right from their perspective.

Instead, thank them for sharing with you that he has been talking about you and your private matters. Tell them you suspected he was gossiping and appreciate that they were able to confirm it. Then self validate to them... "its been very difficult knowing that my experience being married to him has been so completely different from his friend's experiences. I grateful at least that he doesn't treat you the way he treated me!" Then walk away. Don't say anything more. From THEIR PERSPECTIVE, you've behaved differently, spoke differently and acted differently than he described. You will give them reason to DOUBT HIM without arguing or getting upset.

Remember, anyone who approaches you is purposely trying to provoke you into behaving the way he says you do.