Hebrews 6:4-6 is often misunderstood. The people that this applies to have left the faith and have no desire or intention of coming back. If you are feeling remorse and have a repentant heart, this doesn't apply to you.
The core issue here is that you don't trust God or his will for your life. Part of learning to trust him is understanding that everything he does is just and right. If he allows something or someone in your life such as a difficult person, he is doing it because he wants you to grow and learn how to deal with this person. He isn't cruel. Whatever pain or harm you experience from trials is intended for your good so you will grow in character and learn to trust him. Every trial is a test of trusting God.
James 1:2-4 says, "Consider it all joy, my brethren, when you encounter various trials, 3 knowing that the testing of your faith produces endurance. 4 And let endurance have its perfect result, so that you may be perfect and complete, lacking in nothing."
I would advise doing a bible study on your own on the attributes of God, as well as the attributes of Christ. I recommend the book, "The Attributes of God" by AW Pink. https://www.amazon.com/Attributes-God-AW-Pink-ebook/dp/B09FQ9JQFJ
And "Knowledge of the Holy," by AW Tozer, https://www.amazon.com/Knowledge-Holy-W-Tozer-ebook/dp/B09SL7TBVH
Both of those books are classics and they're very affordable if you get them on Kindle.
Blue letter Bible also has a free course on the attributes of God. https://study.bible/courseinfo/27
Here is a core truth to apply to your life. Just keep in mind that there will be times that you fail, as we all do, but continue to come back to the Lord, repent and ask for forgiveness.
Matthew 11:28-30 “Come to Me, all who are weary and heavy-laden, and I will give you rest. 29 Take My yoke upon you and learn from Me, for I am gentle and humble in heart, and you will find rest for your souls. 30 For My yoke is easy and My burden is light.”
You can understand the "yoke" by looking at the picture of a farmer and an ox. The yoke went over the ox so the farmer could direct it when plowing a field. Christ is saying to submit to his yoke, which means to submit to his direction. He reminds us that he is gentle and humble and submitting to him will lead to rest for your soul. His yoke/control over your life is easy and the burden is light. You will find the greatest peace by submitting to Christ.