I have 4 SIL's including 1 on my DH's side. I think this is relevant as I get on with the other 3 married to my brothers.
From the get go it has been a competition (one sided) between SIL and I, fuelled by MIL. She is a couple of years younger than me. The women in my DH's family all create drama amongst themselves and hate each other till the day they die. It is actually very unsettling. I've never seen anything like it. It is like an Italian feud.
A few years ago DH and I fell out big time, and I thought we would divorce. We are still together. When this happened my DH confided in my SIL and she basically took delight in our splitting, and offered to house him when he left and host my DC at her house. On top of this, she posted numerous times on her Instagram of pictures of her in his office where she had travelled over to meet him (way out of her way) to give him some information and help him out. My DC showed me the pictures. All these dates are right in the thick of us discussing the ins and outs of breaking up. Also, during these 3 months of heartbreak non of my PIL contacted me or my DC. So much for caring about their welfare.
Anyway, a few years later we are still together, but I cannot get what she did out of my head. Yes, I also have a marriage and DH issue and that is a whole other thread.
I rarely see her now, and my PIL are not happy about the lack of contact and take it out on me. PIL do this thing that I have seen them do to other women in the family. They are civil to my face, but then the mask drops. So, for example I offered to help them with something the other day, and they declined saying they's rather not do it than ask me. Nice!
Anyway, I have to meet up with SIL on Sat at a family members anniversary dinner and I am dreading it. This is someone who I feel I cannot trust, that given the chance would stab me in the heart and would dance on my grave laughing should I come to a nasty end. In fact, she did once laugh in my face when I was ill and upset. It is not just me too, my DC are not that interested in my in-laws, seeing them for what they are.
Oh, and for the record everything is my fault. It is all my fault we don't have a great relationship even though I get on with everyone else in my family.
AIBU to not want a single thing to do with my SIL and after my last DC leaves home in a couple of years for Uni to say I am done and want nothing more to do with them.