Mother in law from hell coming to visit.

My mil is coming to visit, since my husband and I decided to pick up and move 2200 miles away without informing her. The state we were was toxic, and she was there, and the drama she caused was just too much. Long story short she's a sociopathic narcissistic demon, whose extremely racist( I'm biracial and she drops the N bomb a lot) and she's just vile. She posted my miscarriage all over fb before I had time to grieve or talk to my own family and has said things that cannot ever be forgiven. I 100% want her out of our lives and never to speak to her again. But his elderly grandparents are coming out here, because they paid for my husbands college and we came here the second he got a job offer. Life is really really wonderful here, but they don't believe us. My mil has convinced them my husband is lying, that 1- he doesn't have a job. 2- we don't even have a home and 3- the monthly checks for his education were actually spent on drugs. Yes we've sent them proof of everything but that still doesn't quite cut it for them. So they( the grandparents and the devil) are coming out in Aug. I'm having such bad anxiety over the visit. I absolutely LOVE his grandparents and they know how much his mother and I don't get along, but the grandmother is rapidly declining in health and she probably only has a year left according to her doctors, and she just wants us to be one big happy family during her limited time. Trust me if you met this woman you'd do anything for her. She graciously bought me into her family and has been the grandmother I've always dreamed of. My mil just scares me. I already ordered bundles of sage to burn during her visit because she just has the worst energy. I won't lie I'm really overweight and I'm trying to lose it, I've lost 50 pounds,and joined weight watchers but I still have a long way to go.she opening mocks my weight and when my husband defends me, ww3 breaks out and the grandparents become extremely upset. I'm planning my own strategy, making sure I have reasons to escape from the situation i.e. Have to walk the dogs, for hot to pick something up from the store. I'm also going to prepare the grandparents favorite foods. My husband has reminded me this trip is about his grandparents so they can see how far he's come. Our town is extremely small, and the closest WALMART is over an hour away, compared to the San Diego where they live.we have a wonderful apartment and I've just started decorating and I'm proud of it so far but I know his mother will rip apart our home, my weight, my hair, everything about us. It's what she does. This she be the only visit we get from her for the next 4-5 years. Is there anything I could do to try to make this less painful?