Mil and fil got divorced a long time ago after fil had an affair, it really hurt mil (obviously) and since I've known her since I was a baby I saw how much it hurt etc.
Fast forward over 17 yrs and fil has two teenagers with OW and dh has two dc with me.
We usually go for a short family break in the uk, this year I asked mil and dh if I could invite dh siblings (we don't get to see them a lot and they are lovely kids) mil has said no and that it would be too awkward for her.
I completely understand and she has said if we do want to invite them then she will be quite happy to take a few days off in summer holidays and spent time at ours and do things with kids.
Dh is upset, he understands but is upset.
I think mil is being perfectly reasonable tbh....... Over to mumsnet.