Do your kids go to daycare/kindy/occasional care?
Yes. Until Friday, she was at day care 3 day a week. She begins real kindergarten on Monday, again, 3 days a week, 5.5 hours each day.

How old were they when they started?
18 months.
I am also a SAHM, but I work form home too. We had/ve no friends with similar aged children and she needed the interaction and socialisation. So she went.

Am I being irrational/selfish?
Perosnally, yes, I think you are - sounds like you have separation anxiety. But it is normal to be scared, you need to recognise though that she is clearly ready to go, wants to go and it will be good for her.

They the 4hours to start and see how she fares.