So, very quick backstory - DP's DM and I don't get on. It's a really long story as to why and what has happened but I think the short version is that we are really different people (different religion, different kind of upbringing, different politics, different priorities) and I'm really not the person she ever wanted in her son's life. About a year ago, we had a big blow up over something stupid and I decided I couldn't keep spending time with her and being utterly miserable and tense the whole time so told DP I would rather not have her in the house and would not be going to visit her anymore.
The trouble is that DP can't drive (medical reasons) and doesn't want to drag two kids across country on public transport so just hadn't been to visit. She doesn't want to come to us and stay in a hotel so contact has largely ceased. DP calls her once a week but that's it. Recently SiL called me to have a go at me and thinks I need to "just pull some big girl pants on" and deal with it, because otherwise her DM will have no contact with the DGC. I feel like this isn't my problem but SiL seems to think I'm being manipulative and passive aggressive and using access to DC to hurt DP's M. I don't think I am. I just don't want to see her.
Am I being unreasonable? How much tension/hostility am I expected to soak up for the sake of family contact?