My Husbands Brothers Wife Hates Me And Now Its Affecting Our Children.

We have four children she has been around for the last three when my husbands brother come to the hospital to see our baby she as always waits in the car. At family events she won't even talk to me even if I talk to her first. In Dec. She had their first baby and we still have not seen the baby but everyone else in the family sees the baby all the time. Every time we try to go see the baby my husbands brothers wife says no our eight year old is a mess she thinks her uncle and aunt hate her I just don't know what to do we have been nothing but good to them and my mother in law thinks it's wrong but won't say anything in fear of making my husbands brothers wife mad what should I do?