Toddler & Newborn

I am so angry my 3 year old hit my newborn in the forehead because she “kicked him”.

My son will be 4 in September and I have a 5 week old. He has always been nice to her (gives her kisses, shows his toys to her, waves bye etc) but has been very jealous. He’s been acting out, well even prior to the birth. He’s been just mean in general, and wants things his way will argue and say no. I know his world has been turned upside down by us adding her and our attention has been taken away from him being the focus. We have tried to do many activities with just him and spending special time with him. We started talking about the baby coming early, read many books, showed him babies in public or at daycare etc. I figured it would just take him time to adjust.

My discipline has been warning him using 1,2,3 then time out. If that fails I’ll give him a spank and send him back to time out. I did the same thing tonight with an added lecture about babies and being nice. I am so upset he hit her tonight... I never want that to happen again. Help!