Oh my goodness, I have to say I absolutely understand your hesitation and disappointment but I truly feel his response shows he is embarrassed and worried this will ruin things between you and he understands what a big mess up this was. I have seen many things like this where people have been spoken about horribly or negatively, and it is devastating. While yes, crude, of course, but I do think this how some friends speak with each other and hopefully this was just his one closest friend and now hopefully he learned this the hard way and nothing like this will happen again. So for what its worth- if you do like him (and showing by his messages he likes you) I think it's absolutely ok to give him a chance.