never assume

it made me feel like an ass and its a mistake i will never make again.
mr ex man and i had gotten into a conversation about our first sexual experiences. this was an honest exchange of information between adults who were planning on getting married, not anything cheap or dirty.
i have a funny story how my then mother in law called the day after my wedding to check in on me. when i told her i was fine(not the complete truth, but what the heck do you say to your mother in law?)she told me how relieved she was because the soldier of fortune men were notorious for being "well endowed" as she put it. that story always gets a big laugh when i tell it, but it fell flat with mr ex man. i was kind of confused. we were being open and honest. he had told me a few intimate details that i could have gone my whole life without knowing, but i didnt protest because i know it was in the spirit of sharing. all it gave me was a way too vivid picture of him with his ex wife.
so why would he shut down and withdraw when i told him about my mother in law calling me in the honeymoon suite the day after my wedding? it took a few days for him to finally confess why he was grumpy and uncommunicative: my story about my well hung ex husband made him feel inadequate. his ex wife had told him that his manhood was too diminutive to satisfy her and that was one of the reasons she had stepped outside their marriage.
imagine me slapping the palm of my hand against my forehead. i felt like such an idiot. i had never considered the size of the wand when feeling the magic between mr ex man and myself. if i had, i would have mistakenly assumed that as the 6'4", football player type guy he was, that he was hung just fine. what he wouldnt believe is that i didnt care. not at all. i knew we would be fine and since his ex wife was the only opinion he was basing his feelings of inadequacy on, i figured there was a good chance she was just being a bitch and lying to him to make him feel like shit in an attempt to justify her unforgivable actions.
i wouldnt say this alone caused our break up, but it certainly did not help. i will never tell that story again until AFTER i am married and praised my husband for the well hung stud that he is.
do all men worry about this? was mr ex man just being overly sensitive or was i the idiot for bringing it up?