Hi,
I was so glad to hear from you. I have been wondering how all this is affecting you. You are doing great realizing that you don't deserve this, because you don't. You deserve better, and from now on, expect better.
May I make a suggestion? When you have to see them, do acknowlege them. A simple "Hello. How are you?" with a smile goes a long way. When you were at the church, and walked out while your husband and daughter talked to them doesn't really hurt them as much as it hurts you. They get what they want by your absence and you should stand with your husband when he's talking to them. He should have made sure you stood beside him, as that signifies a united front. That shows them that no matter what they say or do, it will not come between you and your husband.
I understand about the anger and frustration. I still get angry at things here and there, but I don't show it. I find something else to take my mind off of it, and then, after a while, I'm ok, and I know that I did the right thing for me. Because, I am determined not to live my life like that and not let them or anybody else bring me down.
As far as the party at the restaurant goes, I think that is a lovely idea. Invite them and be nice. If they try to engage you in a heated discussion, excuse yourself to the restroom, come back and start on a different subject. Or, "I'm sorry. I'd rather not talk about that right now." Or, "You're asking (or telling) me this, why?", which puts the ball in their court. The less you tell them how you feel, or talk to them about personal issues, the better off you will be. These people will only use it against you. Just enjoy yourself and laugh a lot. Laughter is truly good medicine!! It is good for the soul, and it spreads! And you will feel triumphant that you did not give in to their chirades. And you will feel stronger each time you don't respond negatively to them.
I tried everything with my MIL to stop this outrageous behavior. It hasn't stopped and will never stop. And please believe me when I tell you it has nothing to do with you. It is very possible that your husband is "the baby" of the family or her favorite. She feels threatened by you, and will be in competition with you for her son's attention. She has created this emotional dependence on her probably all his life, and that is why she can do no wrong.
The very best scenario is that your husband and you have a talk with his parents, and lay down some boundaries. No yelling, no discussing, just "This is the way it will be". If they can't respect this, then they will lose contact with him and his family.
I know this is hard for you, because you want answers that you won't get from them. You want to know why. You want to know why you? You want to know what have I done to them? You have all this anger and frustration built up inside of you.
Reading and learning helps a lot, as it gives some reason to their insanity. It helps you understand and find answers to the questions that haunt you. I hope that you find some peace of mind, and make that your goal. Peace of mind.
I hope some of this helps you see things in a different light. Don't get so caught up in their world that you lose yourself. Stand tall and smile.
Write back when you can.