Full disclosure, DH is nice to the point of being a pushover and SIL is, in my opinion, controlling and bossy.
We live in the same area as PILs, who are in poor health. SIL has also moved in the last few years to be closer to her parents. SIL is quite obviously the favourite and takes the piss massively with PILs in all the usual ways. She likes to be the centre of attention and resents any of the other siblings having the spotlight - when you look back at key family events, you can link them to the SIL drama running parallel.
I am on maternity leave with our first child. DH works long shifts where he is on his feet for hours at a time. We live in a property which is charming but rickety, it was long term neglected and we have been doing it up while I've been on maternity leave - workmen etc in and out, having to negotiate taking the bins down a long driveway covered in rubble with a baby in the sling, that sort of thing. Not a big deal really, but I had a difficult recovery from birth, still am not 100%, baby is a shit sleeper and I haven't sat on the sofa eating biscuits nearly as much as I would like.
So on Fridays SIL works for a few hours in the afternoon. She works three afternoons a week. DH also works Fridays, however he works a short shift and is home by 4. SIL works 1-5.
SIL has taken to phoning DH and asking him to go round and put her heating on for her, so her house is nice and toasty when she comes in from work. DH, for a few weeks, did this. At first it didn't really sink in, then one week he had barely set foot through the door and she was on the phone reminding him. Bear in mind I'm alone in the house for much of the week and doing bedtimes as well. He did it another few times, though agreed it was ridiculous. Then two Fridays past, I'd had a shocker of a day. I went out with the baby and came home to find the washing machine leaking, the cat had been sick, the baby pooed everywhere... One of those days. I could have cried. I ran around like a headless chicken, turning on my OWN heating for God's sake, and by the time DH got back I only just had it under control and was desperate for ten minutes peace, just to have a wee and a cuppa. SIL made her usual phonecall as I was regaling DH with my tales of woe, and I'm sorry to say I lost it, told DH that SIL was bone fucking idle and that he was a mug who needed to think about his own wife and baby, who had come back to a soaking freezing house while his sister stepped into her door in comfort. I have never felt rage like it, I could have killed both of them.
So DH went very quiet, but he did agree with me and he told SIL that no, he didn't have the time. SIL just went "OK fine" but the next Friday (this past one) MIL phoned and asked DH if he could nip round and put SILS heating on as she wasn't feeling well and had Sils children and it would save her loading them in the car etc. MIL has chronic fatigue but dances to SILs tune to, imo, the detriment of her own health. DH nearly fell for it, but he saw my face and told MIL that he was busy with his own family and it wouldn't kill SIL to put on her own heating and be cold for half an hour.
SIL is now in a massive huff with us (pointed Facebook vaguebooking, being off with DH when he dropped in to PILs today) and now I'm second guessing myself. On one hand, I still think she's a spoilt cow, on the other hand I think, it's only 20 minutes out of DH's day and it's doing a family member a favour? I don't know if it's hormones, but then I think of how much I've struggled at times with the baby and the house, and how DH's family have been nowhere to be seen and I want to scream at the.