I'm thankful you want to give your life to Jesus Christ -- and I pray you won't turn away from Him, in spite of the difficulties you face. God has put this desire in you because He loves you and wants to come into your life and become your constant companion.
Can you be a "secret" Christian? No, not really -- not even if you wanted to! When we give our lives to Jesus, God Himself comes to live within us by His Holy Spirit -- and from that moment on our lives will be different. For example, God will give us a new peace and joy, and a new love for others. In other words, even if you tried to keep your commitment to Christ secret, in time your family would see the change in your life, and discover the reason for it.
No, you can't be a "secret" Christian -- but you can be a wise one, asking God for wisdom to know what to say to your parents, and how to say it. The Bible says, "There is a time for everything... a time to be silent and a time to speak" (Ecclesiastes 3:1,7). The Bible also says we should tell others about our faith "with gentleness and respect" (1 Peter 3:15).
Jesus Christ loved you so much that He gave His life for you. May you respond to His love by giving your life to Him, and then trusting Him to use you to point your family to Him.