Are left-behind people beyond repentance during the Tribulation

My question ultimately concerns falling away from Christ due to repeated sin issues. I’m curious if Matthew 13:7, Romans 8:13 and James 1:15 connect and describe what has happened to me in my loss of relationship, unrenewal of mind and hardened heart. My questions while reading the following are:
1. Will sin kill a believer spiritually that they will ultimately lose Christ?
2. I what I’m experiencing a sign that I was never a believer and, even though I had know Christ and grown in him for 16 years, that I was not a believer? That the Word was choked out of me because of my sin?

To be beyond repentance is a choice.

Those who come to know God inevitably repent, realizing that God’s way heals whereas going against God’s way leads to many sorrows because sin is a perversion that gets worse with time and also corrupts the soul. It is possible to sin so much that a person changes from a human to an abomination, with the conscience singed of any good and reprobate in mind.

God gives many chances to get right with Him. A person has to deliberately and consistently choose to ignore the Calling (when God knocks in your soul) until it is too late. After death is Ressurrection and Judgement by God Almighty, LORD Jesus Christ. Nothing is hid from LORD God— He Knows!

So get right with God before it’s too late. God is long suffering but He is already Kindled. The time of His Wrath is near. There is no escape from Him whether you die before that time of Jacob’s Trouble or if you do get to witness this part of God’s plan. You will get resurrected and you cannot escape the Summons, when God calls us before Him for Judgment

I have come to determine with a great level of certainty that my heart has hardened past the point of repentance due to continued sin. I feel no brokenness or conviction over my sin nor do I have the desires of the Lord anymore. I find no ability to turn away from sin from a heart level like I once did. All that I am left with is severe fear of my future condemnation. As I read Hebrews, I see that my life now matches up perfectly with Hebrews 6:4, as well as Hebrews 10:26. I have spent time consulting with my pastor and other believing friends. They seem to believe that I am still a believer, but I sincerely disagree. I think they are coming around though.

As I have come to the conclusion that I am beyond repentance, my question is what is the best thing for me to do next. I cannot spend my life walking in apostasy creating greater condemnation for myself upon my death. Life is too much to live apart from Christ. There is no meaning to life other than Christ and there is no joy apart from him. I cannot continue with life apart from Christ. However, I see no other way to handle the situation other than suicide. Does anyone have any better suggestions or wisdom to give?

I know some of you may land in a more reformed camp like I once did, but there is no denial that someone can become like those mentioned in Hebrews. I have become one. What then do I do now?