What you're really asking is this: Is there any sin that is so terrible and repulsive to God that He will never forgive it, no matter how much we ask Him to?
The Bible's answer is clear: No sin -- and no sinner -- is beyond hope. God's grace is greater than all our sins, and no sin is beyond His ability to forgive. I think, for example, of Peter, who was one of Jesus' closest disciples. And yet when Jesus was arrested, Peter publicly denied that he believed in Jesus or wanted anything to do with Him -- and not just once, but three times. But when Peter repented and asked God to forgive him, He did.
Don't misunderstand me, however. The Bible says that before we can be forgiven we must face our sins honestly, confessing them to God and repenting of them, and then trusting in Jesus Christ for the forgiveness we need. Take comfort in God's promise to you, and to everyone who truly repents of their sins and seeks God's forgiveness: "If we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness" (1 John 1:9).
And this is what I pray you will do. Satan will try to convince you it's too late for you to turn to Christ -- but it's not. Don't leave God out of your life any longer, but come back to Him and discover the joy of being His child forever.