I have the same issue. We just call it the mother in law curse

!! I have known my husband for 17 years. Grew up with his family right down the road.
She was SO happy on our wedding day, but literally HATES me now...even as I am ready to give birth to her 6th grandchild by her son!! Hopefully it will pass with yours, but as the other posters have said, try to not let it get to you!! Remember that you are bringing a beautiful baby into this world and as long as you and your bf can stick together, all will be right in your little piece of the world!!!
Good Luck,
Marcie