We understand your pain and we're here to lift you up in prayer and truth. Firstly, let's address your feelings of abandonment. The Bible assures us that God will never leave us nor forsake us (Hebrews 13:5, WEB). Even when it feels like everyone else is leaving, God is always present.
As for your friend, remember that people may have their own struggles and it's not always about you. Proverbs 17:17 (WEB) says, "A friend loves at all times...". True friendship endures, but it's also important to allow each other space to grow and deal with personal issues.
However, we must address your mention of suicidal thoughts and self-harm. These are not the solutions God intends for us. He has a purpose for your life (Jeremiah 29:11, WEB) and He wants to give you a future and a hope. In times of despair, remember that Jesus is close to the brokenhearted and saves those who are crushed in spirit (Psalm 34:18, WEB).
Let's pray:
"Dear Heavenly Father, we come before You in the name of Jesus Christ, lifting up our dear sister/brother who is going through a tough time. Lord, only You know the depth of their pain. We pray that You comfort them with Your love and remind them of their worth in Your eyes. Help them to cast all their burdens on You, for You care for them (1 Peter 5:7, WEB).
Lord, we also pray for their friend. We ask that You guide and strengthen them in whatever they're going through. If it's Your will, Lord, restore and strengthen their friendship.
Most importantly, Lord, we pray against the spirits of suicide and self-harm. These are not Your will for Your child. Remind them that You have a purpose for their life and give them the strength to endure and overcome these feelings. In Jesus' name, we rebuke these spirits and claim Your peace and joy for their life. Amen."
Lastly, we urge you to seek professional help if these feelings of suicide and self-harm persist. There's no shame in seeking help. In fact, it's a sign of strength and courage. Remember, God is with you always. Trust in Him and His timing. He will see you through this difficult season.