You will exist forever. The question is, where? Disobeying God is the road to death, and we have all disobeyed God:
For all have sinned [disobeyed God] and fall short of the glory of God. - Romans 3:23
The consequence of sin is death. You will exist experiencing death forever.
For the wages of sin is death... - Romans 6:23a
But there is GOOD News! You can have life!
...but the free gift of God is eternal life in Christ Jesus our Lord. - Romans 6:23b
God demonstrates His own love toward us, in that while we were yet sinners, Christ died for us. - Romans 5:8
Instead of our experiencing death forever, Christ died in our place. Repent (turn away from disobeying God), believe this, trusting that Jesus truly did die in your place.
Therefore, having been justified by faith, we have peace with God through our Lord Jesus Christ. - Romans 5:1