My family hates my boyfriend cause he younger what should i do?

see i feel in love with this guy when i was in 8th grade and over the years we were so close he has always been there for me with all the problems i have and the past i started to find away to tell him i love him more than a friend and well one day i finally did it and i was so happy... and we have been together for awhile now and well i took him to meet my family and they dont think we should be datin because he is 16 and im 18 its not like we are having or nothing other than kiss and hold hands we dont even touch each other.... i got with him before i turned 18 and they didnt have a problem with him when i was 17 just now i dont know what to do i have always been a big family person but i really love him i dont want to leave him but i dont want my family to hate him either