let me just say i'm 19 and i don't think i'd ever date a 59 year old. my parents and friends would freak. ........
unless you were like george clooney handsome

then MAYBE haha
anyway,
precious -
thats really confusing. it seemed like he didn't want you to go and then he tried to say he told you he backed out just so you WOULD go? he needs to get his story straight and tell you flat out what he wants and why. i personally don't like hanging out with bfs family but that just might be because i'm young. i'd take it as a blessing but the fact that his ex is going to be there would make me a bit nervous. i don't know what his relatives are like or if what he said has any truth to it but i'm sure hes not EMBRASSED OF YOU! thats crazy. if he was, he wouldn't have stuck it out with you.. right? his parents like you too which is a big plus.
besides, 24 and 30 are fine. infact, he should feel lucky because older woman know much more and are experienced.
if this continues to bother you, definately tell him you feel like hes embarassed by you and you want to know his feelings on the matter. its not fair to you for him to be dating you but at the same time embarassed by you! if you get along with his parents, he should have no problems showing you off to everyone else!
if theres still a chance, maybe you should just go. see what his relatives think. if they don't like you, so wHAT. but they have to meet you at some point so it might be good to take this opportunity to meet them.. idk..
good luck though and keep us posted