SIL trying to ruin things

[jumparoo]

My SIL is constantly competing my DW, my DW hates her sister since we found out we were having a baby last year (dd is now 5 months old) she has been not stop in trying to out do anything we do as soon as me and my wife ( was dp at this point) found out she was pregnant she instantly said she and her partner were going to try for another one, about 2 weeks before our due date she then announced she was pregnant( later miscarried) just to get attention because she couldn't stand people being interested in my wife . Every time she comes to our home she slags everything we own off because she can't afford it ( she and her partner refuse to work and waste there money on anything but there bills which FIL then has to pay them). Me and DW got married in Feb when we told everyone the date we we're getting married she ignored us completely because she has wanted to get married for years but cannot afford to, then she messaged my wife trying get involved with the wedding after everything had been arranged, my wife didn't want her involved as she tries to ruin things for the sake of it, but she went running to FIL and he asked us to involve her so we did just to make my wife's parents happy, everyone my wife's bouquet which she did but then charged us for it and it was too a very poor standard, which brought my wife to tears because she just wanted her sis to be happy for us. She then whinged to FIL again saying it was unfair that she was still being left out and that she wanted to make some cupcakes as she is trying to start a cake business, again we asked her to make some just to keep the peace and again she charged us for them. Then a 2 days before our wedding she told everyone her partner her testicular cancer which was a complete lie again just to get all the attention which again put my wife in tears. My DW said she didn't want anymore to do with her but and SIL knows this but every time we try to do anything with PIL she phones them and asks if she can come (PIL know DW hates sis) and again upsets my DW as she thinks she can't have a relationship with her parents ( very close with her mum and misses them a lot as they live an hour away). Now today she has announced she is pregnant again and her due date is around our DDs 1st bday which my and DW both know that the chances of you baby being born on its due date are very slim and you cannot help when you get pregnant. DW is now truly upset and fed up, but FIL gets upset if we have nothing to do with SIL.

she only has this effect on you because you allow her behaviour and you allow others to dictate your response to her.

If i were you i'd encourage and support your dw to remain low contact with sil, it is up to you dw to make it clear to her parents that she wants to see them without sil being present and if they force sil on her then she will just leave and not see them, and that they need to respect her choice to not have sil involved in her life.

when it comes to your home, however, i think you have every right to say sil is not allowed in there unless she can behave like a mature adult - your dd does not deserve to be exposed to such toxic behaviour. hopefully, if your dw sticks to her desire of remaining low/no contact with her then she should have no reason to visit anyway.

It all sounds very childish. You don't have to do things to keep the peace or because fil wants you to e.g the bouquet, the cakes. Keep your distance from sil if she is awful. If fil gets upset about it then so be it.
Your wife is unreasonable to be sad that her sil is having a baby around the time of your child's birthday that is ridiculous. Everyone needs to grow up in this family.