Will my 3 year old feel left out ?

AYDENSMOMMYISEXPECTING

Hello I am 4 weeks along just about I work five days a week. I have a very active son who never sits still enough for a minute. He doesn't listen very well either and I am very tired and still in fear of the morning sickness. I was wondering how to cope with work,housework,child,and other things that may come up. He's always wanting mummy's attention all the time. When baby comes will he hate me how do I split my time? Will he feel left out . How can you explain mommy and daddy have a new baby with out saying it in a way to hurt his feelings?