The title says it all feel empty inside...
The fact is that you have not committed a sin that is unpardonable. The bible tells us clearly how many sin the cross covers. Your whole lifetime of sins.
Heb 9:27-28 And as it is appointed unto men once to die, but after this the judgment: So Christ was once offered to bear the sins of many;
The above verse tells us clearly that the cross is a good life, given for a lifetime of sins.
I once thought I had committed the unpardonable sin, but God kept calling me back to Himself. All of the fears and lies I was told while I had the fear proved to be unfounded. I was told "you will never marry God hates you!", I am now happily married. I was told I would die and go to hell. I now have seen God work miraculously in my life, by His power even seeing some sick healed through my prayer in Jesus name.
I was constantly buffeted by Hebrews 6. Now I see that Hebrews 9:27-28 makes it clear that the cross covers all of our sins, not just ones we commit before salvation. If you have trouble with Hebrews 6 look at Hebrews 9: 27-28 closely, if the cross covers all of our sins, how is the person in Hebrews 6, re-crucifying Christ, the only way they can re-crucify Christ, is to have died in a sinful state. The falling away mentioned must refer to a Christain, who walks away from God, but dies in a sinful state. Not a person who was once a Christian, but fell into sin. A sinning Christian can be forgiven, for the cross is still available.
The unpardonable sin is a state of heart, where no matter what miracle God shows us we prefer to believe a lie. The Pharasies were reproved for they called Jesus miracles "a devil", rather than believe He was the messiah. The unpardonable sin is a state of heart where we are no longer open to God. But know the cross is still available to this person, they just make it of no effect due to their willful disobedience, and lack of faith. You can be saved today, just trust in Jesus, and the cross to forgive you.