Terrible twos?

Hi there! I need some advice here. Long post I know but please help.

My little one turned two last month and has gone from being the happiest little boy, please and thank you all the time, never crying, laughing all day and cuddling everybody - to screaming hysterically, hitting, throwing things and refusing to even be touched by anybody.

On top of that he seems to be going through sleep regression. He has gone from going to bed at 8pm and sleeping until 8am to the total opposite. He will refuse to go to bed, when he does he is out of it four or five times screaming. He will get up three times through the night to shout at us in bed, then will not go back to bed unless one of us stays with him until he goes back to sleep.

I’m honestly at the end of my rope. I have had hardly any sleep and the constant screaming has me on edge all the time. I’m back on my anti depressants because he just screams at me all day and hits me any time I go to comfort him.

I need some advice, its my first baby (although I have a feeling I may be pregnant again - oh dear) and I have no clue how to deal with this.

Picture of him before all of this started, smiling away.