MIL is never going to change, unfortunately. Whether her marbles are going or she is just being cunning, she doesn't seem to understand that the 2 of you are staying together, hopefully for another 25 years.
My sympathy is with you and Mr Red. Neither of you deserve this added stress all the while. I wish Mr Red's brother would get more involved but that doesn't seem on the cards from previous posts.
In the mean time, say words in your head that would not get past the swear filter here, love your husband, fuss your animals and keep on posting :) ((((((♥))))))