We understand that you're going through a tough time dealing with fears and worries about death and the afterlife. First, let's address your concerns and turn to the Word of God for reassurance.
In John 3:16 (WEB), Jesus says, For God so loved the world, that he gave his one and only Son, that whoever believes in him should not perish, but have eternal life. Also John 11:25-26, Jesus said to her, I am the resurrection and the life. He who believes in me will still live, even if he dies. Whoever lives and believes in me will never die.
In Romans 10:9-10 (WEB) that if you will confess with your mouth that Jesus is Lord, and believe in your heart that God raised him from the dead, you will be saved. For with the heart, one believes resulting in righteousness; and with the mouth confession is made resulting in salvation.
It is only by the name of Jesus that we have access to God. Also, there is no other name by which we can be saved (Acts 4:10-12).
Your concerns about death and the afterlife are normal, but as believers, we have hope in Jesus Christ. In 1 Thessalonians 4:13-14 (WEB) we read, But we don't want you to be ignorant, brothers, concerning those who have fallen asleep, so that you don't grieve like the rest, who have no hope. For if we believe that Jesus died and rose again, even so God will bring with him those who have fallen asleep in Jesus.
Regarding your question about relationships, we encourage you to pursue godly relationships that align with biblical principles. In 2 Corinthians 6:14 (WEB) it says that we should not be unequally yoked with unbelievers. This means that as Christians, we should seek relationships with fellow believers who share our faith and values.
About your question on whether we will have bodies in heaven, in 1 Corinthians 15:42-44 (WEB) it says, So also is the resurrection of the dead. It is sown in corruption; it is raised in incorruption. It is sown in dishonor; it is raised in glory. It is sown in weakness; it is raised in power. It is sown a natural body; it is raised a spiritual body. There is a natural body and there is also a spiritual body.
Concerning your question about God turning evil, we must remember that God is love and He is good, as stated in 1 John 4:8 (WEB) He who doesn't love doesn't know God, for God is love. and Psalm 100:5 (WEB) For Yahweh is good. His loving kindness endures forever, his faithfulness to all generations.
Lastly, for your request for reassurance, In Hebrews 11:1 (WEB) Now faith is assurance of things hoped for, proof of things not seen. Also in Hebrews 11:6 (WEB) Without faith it is impossible to be well pleasing to him, for he who comes to God must believe that he exists, and that he is a rewarder of those who seek him.
Let's pray together:
Dear Heavenly Father, we come before You today, to lift our concerns and fears to You.
Lord, we ask for Your peace and comfort to surround us. Help us to trust in You and Your promises. Help us to remember that You are a good and loving God, and that You have a plan and purpose for each one of us.
Lord, we ask for forgiveness for any doubts or fears that may have crept into our minds. Help us to renew our minds with Your Word, and to trust in You with all our hearts. Lord, we ask that You will guide us in our relationships, and help us to seek godly relationships that align with Your will and purpose for our lives.
Lord, we also ask that You will help us to focus on You, and not on our fears or worries. Help us to live our lives for You, and to trust in Your promises for our future.
In Jesus' name, we pray. Amen.