Future Sister In-law is making my pregnancy hell - advice needed!!

So being pregnant after trying is meant to be a good thing... well I thought so to..

My husband and I decided to tell family early we were pregnant as we had been trying for a while and made it known to all.

Also because we were apart of my brother in laws bridal party.. well when we told them she went to the bathroom and cried... when asking my brother in law he said everything is fine with her and not to worry...we told them so she could fill my spot I still intended on trying to go to the wedding just not apart of the bridal party for many reasons including I would not fit into the dress chosen....since then we havnt really seen her and if we did she ignored us and rolled her eyes when we spoke of the baby..

She became uncontrollably rude to first my husband and me but now just me..

My Mother in law and father in law told us that my brother in law said she thought we both tried to sabotage there wedding (baby is due on the 12 December and wedding is on the 8th December)...the in-laws defended us and my brother in law agreed this was crazy...I even brought the bridal party dress! I had made it known from when she asked me that my husband and I were trying to have a baby and so did he.

Well I was asked by my sister in laws Mum to apologies for having a baby and the timing.. stupid me did it.. anyways I was told everything was fine when approaching my future sister in law to give the apology and not to be silly..dah!!!

Things have gotten worst the eye rolling the huffs when we mention the baby.. even when my inlaws mention it in front of her the same reaction. Everyone is scared she will turn my brother in law against the family... not the fact I am half way through my pregnancy and can’t mention my baby without feeling sad...

Well out of the blue I got a text message saying she needed to collect her thoughts and sit down with me to tell me some truths..

Ladies what do I do??

No advice is silly at this point I am stressed about this and stuffing my husband and his brothers relationship...