How to deal with my fiance's parents?

My boyfriend and I are engaged, we are both 20 years old and currently studying at University. Just recently his parents found out he was engaged, he even said it directly that he wasn’t joking either. We both know what it means to make such a serious comitment.

His parents don’t know me very well, neither do my parents know my ‘fiance’ very well. His parents were shocked and angry so they said some horrible things about us, but I’m sure they are just worried and want whats best for him. I’m a pretty timid person and I hate confrontations or causing problems so I’m really unsure how to handle this situation. We are young but we plan to wait a couple of years, preferably after studying and finding proper jobs..depending on when the right time comes along.

any advice/help will be appreciated :) thanks.