My son wont help out with new baby?

am 8 months pregnant, i have a 11 year old(almost 12) year old son. My husband and father of the baby has to go on business a lot for work(at least twice a month) and wont be home to help with the baby. I told my son( his name is Kevin) that he was going to help with the baby( when im busy like doin the laundry or cookin dinner). He refused!!!!!!!! I said "No ur going to change the poopy diapers, feed it(it becuz IDK about gender), play with it, entertain it, ETC. He said "No I hav school, and friends to hang with. I gotta pown them at sports.(what does pown even mean.) I said "No u go 2 school and come rite home to help its more important then friends" He said "Thats selfish, mom i hav friends and we need 2 hang out sometimes" Well how do i make himdo it help me. He has to. I cant do it all myself