So he has a failing, which is the complete and utter inability to stand up to his family in defence of you.
That aside, how's the relationship?
When it comes to failings, you have two choices -
- Try to actively work on the failing, to reduce it or remove it completely.
- To ignore it completely, and simply try to avoid situations where it might become relevant.
Either option is better than -
- Do nothing to change it, nor avoid situations where it might be important, thus causing you to fail again and again.
Stressing out about it privately without taking action to fix it is about as effective as trying to pass an exam by listening to hip hop music. Just don't.
YOU wanting to work on it isn't enough. You're not going to nag him into this. You need to convince him how badly it hurts you in order for him to realise, himself, that he needs to do something about it for the sake of him loving you, and your relationship as a married couple.
Once he realises this, he needs to have some serious sustained conversations with his family with you sitting there by his side. He explains to them that you have been, are, and always will be a significant part of his life, and that they need to accept that shit or they can kiss him goodbye forever.
If you explain how badly this hurts you, and he still doesn't care enough to do anything about it, you need to consider whether his feelings for you are equal to your feelings for him, and think seriously about how emotionally balanced this relationship is.
On the other hand, if you want to go with Option 2, neither of you go to any family event, ever again, ever. You write them off as being a nasty bunch of bitchy cunts, and you sever all contact for the rest of your lives, or until they make amends, whichever happens first.