8 months pregnant and in laws visiting

[Arwen7]

I'm sorry for the long post but I do not know what to think about this situation.

I am 8 months pregnant with first baby. Everything is going well but obviously I am heavy now and tired and all that comes with the end of pregnancy. My in laws (MIL and SIL) decided to come from a foreign country for two months to help. I secretly preferred to be on my own with DP for the last few weeks of pregnancy and the first few weeks woth our newborn but I understand they want to meet the first grandchild and thought some help would be good.

I was not aware (neither DP) MIL has dementia. Not too bad, but can't be left on her own and especially worries if SIL is not around as they live together.

When they arrived SIL told us she is going abroad on holidays for two weeks, that will be when I'll be 37/38 weeks and we are planning a homebirth. Now I'm worried if I go into labour we have MIL to worry about and if we need to go to the hospital only one person is allowed (obvs I will want my DP there with me).
DP mentioned to SIL to help with cooking etc so I did not have all the workload on me (or at least not extra). Somehow it ended up in a row and now SIL says they will leave a month earlier than planned. There is tension in the house as she is behaving all upset and this is in turn stressing me out.
In addition, even though she has provided with some help, SIL seems mainly wanting to go out with friends, etc (for example she left today and not coming back until tomorrow night) and have a holiday out of her time here. DP is dealing with a lot of house renovations before the baby comes and I'm still WFH but now have MIL to look after.

AIBU in thinking that this is all a bit unfair and that to come at this time, create drama and then expect us to look after MIL is just rude and bad timing? Should I just suck it up and DP to share the responsibility of looking after MIL?

So your sister in law and MiL live together and MiL has onset dementia? I'd have done the same. It's a lot for one person, your husband needs to pull his weight as far as looking after his mother. It's terrible timing what with you being 8 months but all in all looking after someone with dementia 24/7 is maddening. All of you are being a bit unreasonable.

@VladmirsPoutine yes it's very mild at the moment. I agree with you, my own mother has dementia but much more advanced.
Maybe if she had told us and/or ask for help it would have been better and we would have taken a different approach. Obviously DP will need to help financially to arrange a full time carer however last time that help was offered SIL declined.