The low down. SIL and DH are not close. They do not call each other, but are happy to see each other when they do. My SIL is not married or has no kids and is in her 40's. We live at opposite ends of the country to them and when they come over, it's usually for a week+. DH's mom and pop are very welcome in my house and my 3 kids love them. The problem is that now they have started to bring SIL with them as she moved closer to them. When she is at my house she will constantly tell my kids off (for things I wouldn't) and seems to have a draconian approach (think Victorian Governess) attitude towards them. We invited them over for Xmas and she came too and spent the whole time telling me/ my kids how spoilt they are and kept making negative comments about their presents and how I went over the top. TBH, my kids really didn't have a lot of things compared to other kids I know, but I really buy into the whole magic of Christmas and all my kids are under 5. . She spoilt the whole day. When she is around either at my place or PIL's we all have to pussy foot around her and walk on egg shells so no one upsets her. MIL doesn't want to upset her daughter for any reason and always takes her side. The other thing that I think is that she gossips to MIL about me and makes snide comments as I have noticed that MIL's attitude towards me sours when we are all together. They also pass glances to each other and raise their eyebrows when I say something or have bought something and will say something passive aggressive like "lucky for some" or "did you ask DH if you could buy that" or something similar. FYI, my SIL did not send my kids a present or want to know them until now and is now all over them like a rash. She also really gets my back up as it seems she's circling like a hawk and then as soon as I slip up slightly she comes steaming down on me. She frowns and then turns to me and says "Err, XXX, why did you do XYZ" like I am a naughty schoolgirl. By the way we are the same age.
We are about to move and will live a lot closer to them. One of the reasons why I am stressing out is because I would be very happy to spend more time with the PIL's but I do not want the SIL around. I am happy to have her over sometimes, but not all the time. She spoils things and I think she is toxic. I think she bad mouths me because I see looks between them and she's the instigator. I also have heard her say really vile things about other relatives in their family that I would never say about my worst enemy, so I am pretty sure I get the same treatment out of ear shot. I get along with my own siblings partners and we have a relationship where we do not get in each others faces. When we see each other we are pleased to do so. I don't see why I have to make myself miserable in my own house. I am not scared of her, but I am scared of upsetting my PILs and causing a problem amongst us. They would take her side even in the wrong. Usually I am a super assertive person and would not let anyone upset me without giving it back plenty. I'd never let a friend or one of my relies treat me and my family in this way, so why is she getting away with it?
AIBU to want to have an at-arms- length relationship with her and not want to have her round all the time when PIL's are there? Any tips for dealing with her?