I don't have anything against my husband's
2 and a half years
Nomally when there is a problem with in-laws I would say it's your husband's job to help the relationship they have with you... But in this case... Something took a wrong turn and you used to be close but things are different now. I wonder if you can approach your MIL and say "I know it's concerning that I have an autoimmune disease, but I'm going to do the best I can to make sure the baby is healthy and I know you will be wonderful grandparents. To be honest, it seems like we're not as close as we used to be and I would really like to have a good relationship again especially before the stress of a new baby. How can we do that?"
In the meantime I think maybe your husband is too sensitive to the relationship change to use him as much of a sounding board for your negative thoughts about his parents, so I might vent to a friend instead...
Welcome to the board, Mgwm ~
I feel like we're missing a lot...there has to be a lot in between your MIL being less than thrilled with a pregnancy announcement two years ago and your husband claiming you don't like his parents if you say anything less than wonderful things about them.