Firstly, you need to rule out any medical reasons for the change in behavior and deal with it.
Secondly, it takes two to have a conversation, a discussion or an argument. You need to be able to disengage from this situation and then develop a very thick skin which takes practice, patience and time.
When OH gets argumentative, I often quite deliberately tune out and my range of 'hmmmms', really? and other responses has become very extensive. Often this sort of behavior is childish so I use strategies that I would use in managing a child. That is not being disrespectful, just accepting the reality of the situation.
When he has been really bad, I have very firmly but always calmly told him to stop talking. He knows from the tone of my voice that I am not going to be messed with and he will usually back off. I know it mightn't work for everybody but anything is worth a try.
If he persists in continuing with the argument, I just tell him that I am not going to tolerate this, grab my keys and go out for half an hour. I generally get some peace afterwards. Just remember that he can only 'argue' with you if you are engaged in it. Let him argue with himself.