HELP- ex boyfriend quierys

So basically my ex was in the military and completely fucked me over a few months back but tonight we happened to be at the same Boxing Day party, we were outside having a heart to heart about why he cheated and I never used to believe a word he said after that, obviously aha so I asked him why did he cheat?? And I kid you not, the second I asked that he stopped shivering like he was shivering like mad and completely stopped when I said that and he answered me with "I completely fucked up, I know I did"