Terrible two's?!

Ok how in the world do you discipline a two year old after he slaps you in the face and then looks at you with those puppy dog eyes and says sorry mama then does it AGAIN! My toddler has been driving me batty the past few days. He refuses to nap, screams all day long and now has begun hitting everyone! The sad part is I have raised two year olds before but never dealt with any of this. My older kids were cool and calm and my oldest still is. I admit my middle child has her moments but she is the only girl and she was the baby of the family for 8 years until we had E. I'm not big on spanking because I feel it just doesn't work. Honestly how can you tell a 2 yr old not to hit if you hit him right! But I have tried time out and let's just say I suck and I'm a total push over! After a minute of shriking like I just beat him on top of him hitting his self and telling me how mean I am I usually end up needing my own time out. I can only take so much before I start to cry myself. I am seriously thinking of calling Nanny 911. I need major help!