How to begin again?

My girlfriend of 2 years cheated on me. I knew it all this time, but i always told myself otherwise. She flinched when i touched her, stopped wanting to have sex and barely talked to me. I desperately tried to find evidence that i was wrong, but i confirmed the truth when i confronted her.

I dont know what to do, i cant stand to look at her, everything we built together is now dreadful to me. I know it will heal but god, i didnt even remember i could be in so much pain.