My gf (25F) of 11 months has cheated on me (27M) with a old flame and I am heartbroken. How would you suggest I proceed?

So basically I found out that she has cheated on me and after 11 months of the best relationship I have ever had she has thrown it all away. I don’t feel like I can ever trust her again as the thought of her with someone else makes me want to throw up.<br><br>She is all of a sudden interested in me, touching me, kissing me and generally showing me love. I have explained that I need time and space but she wants us to go back to normal and says that what happened is in the past and cannot be changed.<br><br>I have been in a daze for the last week and I am struggling to wake up in the morning as all I feel is sadness, my heart is broken and I cannot see us getting through this.<br><br>I am normally a calm person but I am struggling to keep my temper and I feel like I am about to explode at any moment.<br><br>Any advice on how to proceed would be greatly appreciated.<br><br>Tldr; Girlfriend cheated, relationship finished.