I had a similar situation. The deifference being, my inlaws were 20 minutes away. My father in-law even went as far as to try to talk my husband into a divorce! Even bragged about it at my daughters Christening!
It took 10 years for my husband to realize the manipulation that his parents and sisters were up to. FOrtunately for me and my 3 girls, the realization came 6 weeks after the divorce encouraging! Emails were accidently sent to my husband which were ment for others eyes (not mine or my husband). Needless to say my husband was quite shocked at what he read and FINALLY believed me about his family.
He stood up to them and told them it was his life! We were fortunate a job transfer came thru and now were 2000 miles apart! The visits are rough, but there short!
Hang in there! Ask your husband to say something so your not the bad one.