Speak to your partner again, and tell him quietly and reasonably that you find his remarks unkind and hurtful. Ask him why he feels the need to make them and tell him to stop.
If he stops, all well and good.
If he doesn't stop, or starts again shortly, you need to think long and hard about your relationship. To ridicule your partner in public. in front of family and friends, indicates a basic contempt for you, and that is very hard to overcome.
I speak from very bitter experience with my ex-husband, who did this constantly, (can't you take a joke?) to the extent that friends would tell him to stop because he was embarrassing. Nothing I said or did prevented him from doing it; ignoring it, parrying it, tears, anger, silence; at the time I thought it was insecurity, anything for a cheap laugh, too much to drink, but after our divorce I realised the simple truth, that he and his family held me in contempt.
It started soon after we were married; you and your partner have had a good relationship for twenty-five years so I hope this isn't the reason.
Whatever it is, do not tolerate it.