Adde, it's not a tricky question actually. Well, sorry for being a besserwisser. Actually I'm not...
Andy, this things I have experienced myself a couple of times. But I have been a spiritual guidance in my Church's community for some years and I have encountered people who had been through this too.
I try to give you some of my advices. First two questions. If I'm not wrong she's your wife's sister your talking about.
Is she married? Or is she living alone? Does she have own children? It's not necessary at all to answer this questions actually. They are just for my advice's reasons.
My brother is married with a lovely woman and they have two twin girls. I have accepted the fact that I don't get any of my own children because of my troubles with men.
Actually I'm recommended for not getting pregnant att all, that can actually kill me according to my doctors. I have accepted that too totally.
For me it's hurtful to see my brother's joy and happiness with his own family, just because I know that I can't have my own family. We rarely speaking nowadays about his twin girls at all while we talking with each other in the phones. We talking with each other daily actually.
Sometimes he takes up news about the girls in our conversations, but often I start to cry. We all are different from each other, nobody feels the same as others.
Maybe she's like me? My advices I'm giving you is that not turning your back, that's the worse somebody can do. Ignoring someone is hurtful as bullying someone.
It's a good thing to be friendly because of your wife, but if it's not okay with you, it's okay to unfriendly too. Remember that everything is not just black and white when it comes to ours feelings and emotions, between those two colors you have the whole rainbow's colors.
Just be open with your thoughts to her, balance your feelings for both you and your wife. I'm not sure if this advice is good, but I think a longer talk between eyes (in real life and not by texting) can solve your the emotions and feelings you have.
Remember, respect is the most important thing, and avoiding ignoring is important too.
My older grandfather passed away this Thursday, it was for his fellow soldiers I did the pray at the monument in Tver, my friend took a photo of me standing there praying. I wanted to show him that, to encourage him to live.
I was to late. That's very painful for me actually, I regret that so much actually. This shows how fragile our lives is. Hopefully he knows that in the Heaven... I miss him...