To be upset about this...

[verytiredmummy1]

Without drip feeding and without outing myself ...

When I met DH I got on really well with SIL. She had form for not being the friendliest of people so I was pleased we got on. All of sudden a couple of years ago she stopped talking to me and now won't even acknowledge my existence. It's awkward at family events and is now a thing. If I say something to her she won't even look at me and if I'm involved in a conversation with MIL for example and SIL is there she will ignore my contribution to the conversation and talk to MIL like I haven't said anything!!
Everyone knows she won't speak to me.

I'm not upset as such just really puzzled as to what happened?! I've got no idea!! DH says to ignore it but it's just so awkward and I've got no idea why. The intrigue is irritating me.

Should I just leave it?

Unless you are on mumsnet SIL in that case it didn't upset me at all

"DH is worried about causing a rift in the family. It's his brothers wife."

So, why are they more worried about upsetting her than you?

Perhaps cut back on visits to them when SIL is there and tell them why.

Unless there is some kind of psychological issue she shouldn't be behaving like a 6 year old.

Like PP I can believe that the SiL happens to be a massive cunt the most ridiculous part is that everyone else just accepts it. Why hasn't DH pulled her up on it. It must make things incredibly uncomfortable for the entire family when she's ignoring you at family occasions.

I'd be very pissed off that at my own child's partying particular she'd be such a cow. Was thd party at your house?

*party, in particular.

Party was at in laws house as they wanted to throw the party. I've left feeling bitter and resentful and like maybe PIL actually don't like me. Otherwise they wouldn't let me be treated like this.

This is more than being a bit off, she refuses to acknowledge your existence when you have invited her into your own home.

Calmly ask her why she does this, I would have to know, then agree to ignore each other.

Awful that the rest of the family lets this go.

Just seen it was PIL's house but still ridiculous behaviour from an adult.

In front of everyone

"oi Sil what's ya beef?"

Why should the husband talk to her? Her issue is with the OP so it's the OP who needs to address it. Why on earth is itv being suggested a woman hides behind a man?

Why hasn't your husband asked his brother what the hell is going on?

"Oh did you not see me? Bye SIL" in sarcastic but sweet voice.

You're resentful at the PIL's?? Why not at your husband who hasn't addressed the issue with his brother and stood up for his wife?

or resentful at the SIL who's behaving like a child and you're not addressing it directly?

She is clearly a massive prick! But I think you either have to a) ignore her completely and not make a thing out of it, not show any emotion, don't acknowledge it, don't talk to anyone about it. Or b) pull her up in it (probably publicly) and find out why she is being a prick.
Personally I would probably take option a) as I hate confrontation and if someone was that much of an arsehole I wouldn't give a flying fuck about never speaking to her again.