We are truly saddened to hear about the situation with your sister and the burden you are carrying. Firstly, we want to remind you that it is commendable that you are seeking help and prayer, but it is important to ensure you are seeking God's help through His Son Jesus Christ. It is only through the name of Jesus that we can be saved, and it is through His name that we confidently approach God.
It's clear that your sister is in a dire situation, and it's important to approach this with both compassion and wisdom. As Christians being responsible for each other is important, but your health and well-being also matter. It's understandable that you feel overwhelmed, especially given your own health struggles and the complex history between you and your sister. The Bible reminds us, "Bear one another's burdens, and so fulfill the law of Christ" (Galatians 6:2 WEB).
However, it's also crucial to set boundaries, especially when the other person has caused harm. The Bible says, "If anyone does not provide for his relatives, and especially for his immediate family, he has denied the faith and is worse than an unbeliever" (1 Timothy 5:8 WEB). Yet, this does not mean compromising your own safety and health.
Regarding your sister's actions and the fact that she has done bad things to you, we must remember that God calls us to forgive as we have been forgiven. "For if you forgive men their trespasses, your heavenly Father will also forgive you. But if you do not forgive men their trespasses, neither will your Father forgive your trespasses" (Matthew 6:14-15 WEB). However, forgiveness does not mean enabling harmful behavior or putting yourself in danger.
Concerning the drug use and living situation, it's important that she be encouraged to get help, as the Bible says, "Do not be deceived. 'Evil companionships corrupt good morals.' " (1 Corinthians 15:33 WEB).
Let's pray together:
Dear Heavenly Father,
We come before You in the name of Jesus, lifting up this situation with our sister. Lord, You know the depth of her struggles and the pain she is experiencing. We pray for Your intervention in her life, that You would break the chains of addiction and bring her to a place of healing and restoration.
Lord, we also pray for wisdom and strength for us as we navigate this difficult situation. Help us to set boundaries that honor You and keep us safe, while also extending forgiveness and compassion. Guide us in how to best support our sister, whether that means helping her find professional help or trusting her to Your care.
We also pray for those who may be judging us, Lord. Help them to see the complexity of the situation and to extend grace rather than blame. Ultimately, we trust that You are working in all things for the good of those who love You and are called according to Your purpose.
In Jesus' name, we pray. Amen.
As you move forward, trust God and remember the promise of Jesus: "If the Son therefore will make you free, you will be free indeed." (John 8:36 WEB)
If you feel overwhelmed, we will continue to pray with you. Please consider speaking to your sister and encouraging her to seek help, perhaps through a local church or Christian counseling service. It is important to keep God's Word in these matters.
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. 
