parenting question

How do you give enough of you time to each kid so the other don't feel left out. before i had my son it was so hard to give my two step kids equal attention becuase they were bother older and i found things we all could do together and they still had one on one time, now that my son is here is needs alot of my attention. He was born a whole month early and just came home sunday, he is a very needy baby and alot of my time is spent taking care of him, i breastfeed and that also is time comsuming. my step daughter was telling her dad that she feels like i dom't love her anymore since the new baby is here and that not true at all it just really hard right now trying to give them all equal attention, she was the baby and now she feels he has takinng her place. like today was really hard for me i had to cook thanksgivng dinner for everyone while trying to tend my son and keep the kids happy but step daughter just wasn't happy becuase i wasn't playing with her the whole time so she went and told her dad how she feels and i told him that i feel bad that she feels that way and that i am doing the best i can but it's hard trying to do it all. well he got mad and went off the deep end that its not that hard to take care of a baby and two kids and that a newborn isn't even that hard to take care of and this that and the other, but what he don't get is is am the one doing it all, i do everything for our son and his kids the on'y thing he does is play with them. so my question is how do you give all of your kids equal attention so the other don't feel left out and how do you keep yourself from not getting so stressed out