The simple message is definitely 'start asserting yourself, politely and see what happens.'
Getting more specific, a simple switch-around would be 'how would you like it if I tried to humiliate you / had a go at you / started an argument, in front of my friends?'. (You do have friends, who the two of you spend time with together? He does give them equal respect and attention as you do his?). Then do it, to illustrate.
If he's the type only to believe the evidence of his own experience (like a depressing number of people, especially men), he may not truly 'get it' otherwise.
The thing is, the scenario you describe here, of him contesting something with you, in front of his friend, is so very, very nuanced and so very, very normal in a lot of families and relationships.
So many family gatherings include tales of 'you won't believe what so and so did' and low level humiliations and put-downs, which, if done in good humour and fairly equally, are not bad or unusual.
Lots of people tell these sorts of tales, or present arguments to an audience, for an outside point of view, with freinds. The crucial point generally, is that they are friends of the person being sent up or argued with, so they form a supportive and knowledgeable audience. 'What are you like! That's so like you. What are you thinking? Remember the time...'
It sounds a bit like you catastrophise any disagreement.
But also like he might be taking advantage of that.