My in laws are sooo fucking fake!

My mother and father in law are nice people but my sister and brother in law and my brother in laws wife are fucking fake they act like they're all nice to me when my boyfriend is around but it's totally different when he's not here.

- back story:

I'm sitting in the den watching tv I'm sitting in a chair where you can't really tell someone is in the room or not and my sister in law (18) starts talking about me and my boyfriend and she feels my son (who I'm still pregnant with) will be a bad kid and have an attitude and temper and I'm just sitting here like WHAT THE FUCK.

My brother in law and his wife just had their first baby together (she has 2 well behaved kids from her previous marriage) in February and he's a wonderful baby I love him to death but I feel like everyone favors him and they aren't to concerned with my son they never asked when I'm due never asked to feel the baby kick or how my appointments go after they found out I was having a boy and not a girl they were just like "eh okay" like because I'm having a boy not a girl he isn't as important as my brother in laws baby and it's sad bc I love that kid and my boyfriend just thinks I'm being defensive and I don't think I am and ugh it's just so frustrating!!