That's a very good question. I'm not a Mormon so I guess I wouldn't be the right person to answer this, but as a Christian I can give my personal advice. 
 
I have in-laws exactly like this, and the only thing you can do is turn the other cheek, treat them as respectively as you would want them to treat you, and don't give in to their bullying.  
 
I know it seems hard and you wish you could just fix everything, but this is not the kind of reasoning that would lead someone to church. You could confront them perhaps, tell them exactly how you feel and that you wish they'd just be nice to you. 
 
Hope this helps.

It seems you have experienced how the church can be perfect but the people who go to the church are not perfect! That's why we go.  
Your in-laws may be feeling hurt and taking it out on you. Not the right way to act but it is happening just the same. It sounds like you know alot about the church so I am sure you know that we believe that families can be together forever. They want this blessing for every single one of their children and see that you and their son will be parted at death not to have eternal happiness together. Their actions are not right but maybe it will help you to see why they are acting that way. It is right for you not to convert if you do not believe the truths of the church. You must do it for yourself not for family or to make someone happy. Maybe your hubby could remind them of the love of christ and how much you would like to be with the family and not always feel like they are pushing. Remind them that they taught him well and now it is his time to make his own choices, just like heavenly father has done with all of his children, they need to love you, support you and hope and pray that your choices will lead you back to our heavenly father. Because isn't that what we are all here to do? I do not believe that Heavenly Father wants to save just some of his children. He wants us all to return to him. And loving and being supportive is how we can all hopefully make it back to him.

Deana~ 
 
I too had this same problem with my husbands family. When I married this wonderful man I was not aware of the baggage that came with that decision. I was faced with stanch Catholic inlaws that didn't even acknowledge we were even married. For many years I lived under the scrutany of his mother and many well meaning aunts, uncles, brother/sister in laws etc... And like you it always seemed they would wait until he was out of the room to quietly "knife" me to death with their snide comments and ridicule. It really took a toll on our marriage for quite some time until I realized...like an epiphany...I don't have to do this! Originally I would get hurt and run to my husband with their comments which of course they either denied all together or attributed to my easily hurt feelings or my inability to discern sarcasm....whatever! Finally, I realized this...when the ridicule starts flying, I walk away or excuse myself to the bathroom or I go for a car ride. You see where this is going? They can only offend you if you choose to be offended. If you walk away, you leave them quarrelling with themselves and if your mind is at peace with your decision it allows you a little peace of mind and it allows your husband a little too since you won't be asking why he doesn't just stay glued to your side or defend you once in a while. It's worked for me now for twenty years and counting...of course in our situation, we are now both Mormon converts. Finally, my husband is having to learn this very same lesson in dealing not only with my family but also with his own. Best wishes to you!! Just make decisions that effect you and your husband and don't worry about the rest of them. They'll get it or they wont....it really doesn't matter much in the grand scheme of your relationship unless you allow it to cause a rift between the two of you.