My wife and I are foster parents, OP I know what you're feeling, hopefully you can get over this, hang in there.
This will be a bit long, so read it or not, it's your call!
Our situation is a little different, when we first started, we said we only wanted one child.
We get a call one day and was asked if we could do two, a brother and sister, she was 2, he was 18 months.
The agency pretty much put pressure on us, telling my wife that we had until the end of the day to make a decision.
We took them in, and waited to see what would be next for them.
When we started we had the intention of fostering a newborn who's family is close to my wife's family, they all grew up together so, they considered each other family.
As it turned out, the newborn was placed with a different family.
One day we got a phone call about the newborn, their grandmother, who already has the first two that her daughter had, requested to the agency that the newborn was with that she would like for us to foster.
Other agency didn't listen to her request at first, but every thing worked itself out.
The 2 that we had ended up going with one of their aunts.
We now have the newborn.
It was bitter sweet when the first two left, we worked hard to improve their life, the 2 year old just mumbled when she spoke, called everyone she met either mommy or daddy was the only clear words she said. That was heart breaking at first, we realized that she and her brother had no idea what was going on.
Within the 3 months that we had them, you could now understand about 80% of what she said.
I just hope that their aunt can take care of them, and will truly love them, they deserive it.