Hi, I'd like to help you with your question.
It sounds like you may be right about your mother having a personality disorder. Unfortunately, personality disorders are some of the hardest to cope with because the person usually lacks the insight to see that there behavior is damaging, to them and the people around them.
Your mother learned her behavior from somewhere, most likely childhood. When children grow up in a home that has some form of abuse- emotional/psychological, physical or sexual, the child learns to cope by reacting in dysfunctional ways. They are not taught normal behavior and they also do not get their needs met. So they learn to manipulate or in your mother's case, put others down, so they feel better and get what they need. In your mother's case, she needs to put you and your wife down so she feels superior.
Unless your mother can see that she is damaging her relationship with you and your wife, she will not get better. You are unfortunately looking at the same behavior from her for as long as she is able to dish it out.
So your only option is to decide how you (and your wife) want to respond. Because you have been treated this way by your mother for your entire life, you have been essentially abused by her. Adult children who have been abused often feel the need to still associate with their abusers because they are their mother, father or some other important relative. But that is not true. Just because she is your mother does not mean you have to put up with how she treats you.
If you must have contact, consider the few sentences you are willing to communicate to her. Something neutral and non provoking. If she tries to provoke you, ignore it or leave and tell her why. Get your business done and go. If you do not have to have contact, then you may want to keep to yourself. You are not obligated to see her or have contact with her. This does not mean you do not love her or care, but her behavior does not allow you to express those feelings so keeping to yourself is the only way to protect yourself.
If you feel that the effects of your mother's behavior has caused any issues for you, consider seeing a therapist. Even just talking out how you feel for a short term helps you have the guidance you need to feel better and move on with your life.
I hope this has helped you,