We are truly saddened to hear about the situation you are facing, and we are here to pray and provide biblical guidance for you.
Firstly, we must address the issue of your fiancé's behavior. It is clear that he has strayed from God's path, engaging in drug use and an inappropriate relationship with another woman. This is not aligned with God's will for our lives. The Bible tells us to flee from sexual immorality (1 Corinthians 6:18, WEB) and to avoid those who practice evil (Psalm 141:4, WEB). Your fiancé's actions are not only harmful to your relationship but also to his own spiritual well-being.
We must also address the issue of domestic violence. It is never acceptable for anyone to harm you physically. The Bible tells us to love one another and to never repay evil for evil (Romans 12:9-17, WEB). It is important to seek help and protection from such behavior.
Regarding your decision to drop the charges against your fiancé, we understand that it comes from a place of love. However, we must remember that true love does not enable sinful behavior. Instead, it seeks the best for the other person, even if it means facing the consequences of their actions. Consider the words in 1 Corinthians 13:4-7 (WEB), "Love is patient and is kind; love doesn't envy. Love doesn't brag, is not proud, doesn't behave itself inappropriately, doesn't seek its own way, is not provoked, takes no account of evil; doesn't rejoice in unrighteousness, but rejoices with the truth; bears all things, believes all things, hopes all things, endures all things."
Let us pray for you:
Dear Heavenly Father,
We come before You today, lifting up our sister in Christ who is facing a difficult situation. We pray for her fiancé, that You would convict his heart and turn him away from his sinful behavior. We ask that You would break the chains of addiction and free him from the stronghold of drugs. We also pray for the other woman involved, that You would bring her to repentance and heal her from her violent behavior.
We ask for Your protection and guidance for our sister. Give her the strength to make wise decisions and to seek Your will above all else. Help her to love her fiancé in a way that honors You and does not enable his sinful behavior. Comfort her heart and wipe away her tears, replacing them with Your peace and joy.
We ask all of this in the powerful name of Jesus Christ, who shed His blood for our sins and offers us new life in Him. Amen.
Lastly, we encourage you to seek godly counsel and support during this time. Surround yourself with believers who can uplift and encourage you in your walk with Christ. Remember that God is faithful and that He will never leave you nor forsake you (Hebrews 13:5, WEB). He is your strength and your hope, and He is the only one who can bring true healing and restoration to your life and your relationships.
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. 
