Nervous / guilt for my first born

I have a 4 year old son who has been my world since the moment he arrived .. He has the most amazing spirit and I have this overwhelming since of sadness and guilt knowing it won't be just us anymore . Fearful of how he will adjust and praying it doesn't change who he is .. I'm over the moon happy about this new baby but I can't shake this feeling that I'm having , I find myself going into his bed while he is sleeping just to snuggle because I miss him (yes crazy I know crazy) I feel like a chapter will soon be ending and a new one beginning .. I pray he doesn't resent me . I'm 6 wks 1day and I know my hormones are raging so I'm praying these emotions settle .. Can anyone else relate ?!