Let's be real about this - families can chat happily about the same-sex relationships of friends and celebrities, but will often have a different reaction when the gay relationship is suddenly in their own family - and it is their own child who is coming out.
Your parents might initially be very confused and shocked - in the way that any of us are when something we thought was one way, turns out to be quite different. But letting those who love you come to terms with a new and significant piece of information is not the same as seeing their reaction as evidence of homophobia.
Your parents' early emotional reaction does not mean that they don't love you or that they are rejecting your choice or abandoning you. They are very likely to go through various stages of the grief processs - and you will do best if you accept their right to process a change to the script they had of your future.
Shock can be a first response, often followed by a degree of denial (where they might say that you are just 'confused', or that you 'need to talk to someone') - or they might be angry or they may start to blame themselves.