My in-laws live 7,000 miles away. I highly recommend it!
My parents live about a mile away, and my mom can be a bit the same way. In fact, H and I are both pretty sure we're living in our current house because it's the one SHE liked.

I was finishing obligations in Washington while he moved ahead to the midwest to start his new job; he and 3 of the kids lived with my parents, and he felt obligated to let her come along house hunting, since she was providing him with room, board, and babysitting. Absolutely nothing pleased her till this one, and we both know her well enough to know there'd be no end to the criticism of whatever house we picked. She absolutely wears people down with her complaints. It was easier just to go with it.
My first thought is that your husband really has to be the one to stand up for the two of you. It is his place to talk to his family. My second thought is that that means I'm the one who needs to talk to my mother, and that is incredibly hard to do because she goes into the self-pitying mode and I know everyone in the entire family will hear about it for the next 13 years, that I was so mean. Fortunately, my mom is too involved in her church activities to put too much energy into us.
Fortunately also, H and I are on the same page. We do visit on every holiday (although not Valentine's Day!

) and if she gets irritable or gripey, we just find an excuse to leave. It's kept it pretty bearable.
Good luck. In-law issues are hard. Even from 7,000 miles away, my sister in law has wreaked horrible havoc in ours.