I suspect my mother in law is sabotaging my relationship with my husband. She's very two faced and likes to twist everything I say. But she's very nice in front of me. What should I do?

This is a very tricky situation. When my MIL behaves like this, I will normally question her directly why did she twisted what I said. After a few times, she knows she can't play 'fire' with me and she finally stops doing it. I feel proper communication with MIL and let MIL understand my expectation is very important, i.e. do not backtalk of me in front of my husband. I also raise the concerns to my husband and my husband understands the actual situation.