I have noticed over and over the suffering from fearing this sin. If you think about it, it's a blessing in a way to insure you are saved because you definitely believe. If you didn't believe, you wouldn't fear this thing. You are definitely saved when you believe in Jesus NO MATTER WHAT YOU'VE EVER SAID or THOUGHT or DONE or DREAMED. God is love. Love wouldn't punish you in a river of fire forever. I remember seeing the man that was in a cage overseas and I believe it was a terrorist that was setting him on fire and he was trying to back up inside the cage but there was only so far he could go. It was one of the sickest, most hateful, horrible things a person has ever had to go thru and it upset me terribly. God wouldn't do that. He would love you. Besides that, even if you weren't forgiven, you've already paid for it by worrying about it so much but you are forgiven. The river of fire is the second death so you don't suffer it forever but again, you don't need to fear it because it will never happen to you. I myself have suffered so badly with this that in 2009 I was unable to function. I have said things, bad things. But I was able to overcome it and I want you to be able to move past it also. If you believe that Jesus is the Son of God, you are saved. It says so in the Bible. Let this fear go.