We are so glad you have taken the first step to reach out and want Jesus back in your life. It is only through Him that we can be saved. As it is written in Acts 4:12 WEB:
There is salvation in none other, for neither is there any other name under heaven, that is given among men, by which we must be saved!
First, let us address the issue of masturbation. While the Bible does not explicitly mention masturbation, it does speak clearly about sexual immorality and lust. Matthew 5:28 WEB:
But I tell you that everyone who looks at a woman to lust after her has committed adultery with her already in his heart.
Masturbation is often accompanied by lustful thoughts, which are sinful. Therefore, it is important to flee from this temptation.
Now, let us pray for you:
Dear Heavenly Father,
We come before You today in the name of Jesus, lifting up our brother who is struggling with the cycle of repentance and masturbation. Lord, he has turned to You, wanting to be clean and saved. We ask for Your forgiveness and mercy upon him. Strengthen him through Your Holy Spirit to overcome this temptation. Help him to cast off the works of darkness and put on the armor of light, as it says in Romans 13:12 WEB.
Father, we also pray for his anxiety and isolation. Help him to cast all his anxieties on You, because You care for him. Guide him back into fellowship with other believers, that he may be encouraged and held accountable.
We ask all this in Jesus' name.
Now, let us address your feelings of isolation. It is crucial to remember that God wants us to live in community with other believers. Hebrews 10:24-25 WEB:
Let us consider how to provoke one another to love and good works, not forsaking our own assembling together, as the custom of some is, but exhorting one another, and so much the more as you see the Day approaching.
Isolating yourself is not the solution. Instead, seek accountability from trusted Christian friends or a mentor. Share your struggles with them and allow them to support and pray for you.
Remember, God is faithful and just to forgive your sins and cleanse you from all unrighteousness. 1 John 1:9 WEB:
If we confess our sins, he is faithful and righteous to forgive us the sins, and to cleanse us from all unrighteousness.
Whenever you feel tempted, call out to God. Psalm 18:6 WEB:
In my distress, I called on Yahweh, and cried to my God.
He will hear your cry and help you overcome. Stand firm in your faith and keep your eyes fixed on Jesus.
Lastly, consider the words of Paul in 1 Corinthians 10:13 WEB:
No temptation has taken you except what is common to man. God is faithful, who will not allow you to be tempted above what you are able, but will with the temptation also make the way of escape, that you may be able to endure it.
God will provide a way out. Trust in Him and stand firm. Keep fighting the good fight of faith.
Prayer Focus: God, Thank You. Thank You for loving me. God, I ask You in Jesus’ name bless me with everything that I stand in need of and everything You want me to have. Bless me to know You in truth, fall in love with You with all my heart, mind, soul, body, and strength and never fall out of love with You. Bless me to have an ever growing closer stronger, more intimate relationship with You. Bless me with the love, desire, strength, and the spirit of obedience to always delight myself in You, seek first Your kingdom, and Your righteousness. Help and strengthen me God to always respect and obey You. Bless me to trust You with all my heart, acknowledge You in all my ways, and lean not to my own understanding. 
