We were on a break, I thought it was over, had a one night stand, he came back?

HE wanted a break, is what you said. that means that if he wouldn't have requested a break to ease his little heartache, your one night stand wouldn't have happened and he wouldn't have a big heart ache. tell him to get over himself and quit being a baby. you weren't wrong in doing what you did. tell him that will teach him a lesson about "breaks."