Can you believe this shmuck???

So an old friend (also old fling) drops into town for training so we meet to catch up on old times. That night, we tried to have sex but it was so awkward (mainly because he was very bad) that I ended up just saying it's okay, don't worry about it. Well we decide to out last night due to him leaving the next morning.... I had already decided that we were not going to sleep together again, I bring my sister, thinking this is detour any presumptions. Well, we all drank too much and ended up just staying in his hotel (which has a king size bed and fold out couch, lots of avail seperate sleeping areas) so we wouldn't have to drive. First... I wake up to him running his hand across my stomach, I just shrug him off and go back to sleep. Morning comes around and he progressively tells me about how my sister and him went skinny dipping... So I ask the question: You didn't sleep with my sister did you? With his "matter of fact" tone, he states yes. For a few minutes I think he is joking but unfortunately not. I state I can't believe you did that and his reply, ladies and gentlemen was.... Well, you were asleep. All of this from someone I have known for 10 years. I wrote him off then and their. So my question is... Can you believe this shmuck??? What are your opinions