My sister in law is the same way, when she found out I was pregnant she was so immature as to say "well why should I even have a baby if hers is going to be the spotlight child" and then I found out we are only 2 weeks apart and I just have no choice but to ignore her and my brother completely
This also happened to me with my brother in law wife during my first pregnancy...she was having a girl it was her third and i was having a boy it was my first and she would always compare our weight and make rude comments how i looked bigger and for delivery she often made me feel like a failure because i had to have a csection. One time she made a stupid comment saying how she wanted to be pregnant so badly and i just got pregnant without even wanting a baby like it was an accident i told hubby about it and he got furious bc of the stupid things she would say and also because we had trouble to conceive we had been trying for a little over two years for her to say that...Our kids are two weeks apart and she often tries to make me feel like a piece of s*** mom she yells at her kids but yet she feels the need to act all nurturing to my son and treat him all nicely like shes always trying to make herself look like she could be a better mom to my son than i am... Now im so over her BS seriously after she tried stealing my son's gold baby bracelet and i caught her she doesn't even come near my son anymore even my hubby told me to not let her near my son since his little wrist was all bruised up from when she was trying to yank the bracelet off his wrist. Sometimes it is childish but just ignore her she will tire out :)