Kitten and Momma at separation advice needed.

So we had an accidental pregnancy. She had 2 kittens. Kittens are now 8 weeks old. Took everyone to the Vet for shots and get mommas spay scheduled. The vet recommended i separate the kittens and momma. They have been separated for 2 days now. Momma howls all day and night. She is trying to get to them. Nobody is sleeping. Not even the dog lol. How can I help her?