MN virgin, please be gentle.
Bit of background: I have a difficult relationship with my sister. She has MH issues and has been very difficult to have a relationship with since we were children. I have often tried to get closer to her now we are both adults but I feel the more I give the more she asks for and takes. To use a MN phrase she acts very entitled. She has literally never looked after either of my children, she says they make her very tired. I have helped with her child since his conception, literally going to midwife appts, being present at his birth and taking time off work to help her to adjust to motherhood. Truthfully this did bring us closer but the more I give the more she asks for IYSWIM.
I have 2 children, 12 and 2. I've taken some time off work to help my 2 year old transition into nursery and to overcome some attachment issues. We can only afford this for a short time and I'll be back at work in March.
Today my sister called to say she has been offered some work 2 days per week starting tomorrow. She would like me to support her in this by having her son whilst she goes to work. The problem is she lives 1hr and a toll road away and her child has to be dropped off and collected from his school. I have no problems looking after her child, I love him to bits. My problem is it will take several hours out of my day and cost a fortune in petrol and toll fees. Money we just don't have whilst I'm off work. If I asked she would agree to pay me back for these expenses but the reality is I will never see a penny. We have loaned her thousands and have never had a penny back.
This will also be difficult for my dd, sitting for literally hours in the car will be stressful for both of us.
So my question is IABU, and how do I say no without causing WW3 just before xmas.
Thank you for reading this far.