Girlfriend left me after fighting. what to do?

I had a big argument with my girlfriend yesterday evening. We were at a club with our friend group. I got super drunk because of work pressure. I only did it to relax.

I went to the washroom to pee and when I came back I saw my gf standing with her back towards me. I was super drunk and I cuddled her from behind.

Big mistake. It was not my girlfriend but her friend. I got confused because both were wearing similar dresses and it was a little dark. Also they have similar physique.

My girlfriend threw her drink on me and started walking out of the club.

I tried to explain that they had similar outfits but she said that she is wearing mauve while her friend was wearing purple. It was so dark and I couldn't understand the colour difference, both looked purple to me.

She left after fighting. I apologized to her friend and she is okay with it.

but my gf is saying that she hates me and has blocked me on whatsapp. What should i do?