The above poster is right, you're not studying for your family - you're studying for yourself, and as the above poster also says you still have time to cram in your revision.
As for your parents, different parents have different reactions to grades. They may be more supportive than you think, or yes I suppose there is a possibility that they could act as though they are disappointed, however the bigger picture is that:
a) your parents will always love you, and any initial negative reaction to lower-than-expected grades will only be temporary and will not last
b) your grades don't actually affect anybody except you
c) even if your grades are lower than you would have hoped it certainly isn't a complete disaster. There are still SO many other paths you can take, not to mention resits being the most obvious first step.
Try not to worry too much and just focus on getting your revision done. Do the best you can do, and then at least you'll be proud of yourself knowing you put your all into it, regardless of the outcome.