We are truly sorry to hear about the pain and manipulation you've experienced. It's important to remember that God's word is never intended to be used to manipulate or harm others. The commandment to "Honor your father and your mother" (Exodus 20:12 WEB) does not mean that we should follow them into sin or allow them to harm us emotionally or financially.
Your parents' actions were not in line with biblical principles. Gambling is not endorsed in the Bible. Instead, we are called to be good stewards of our resources, 1 Corinthians 4:2 WEB Moreover, it is required of stewards that they be found faithful. and to avoid the love of money, which is a root of all kinds of evil, 1 Timothy 6:10 WEB. For the love of money is a root of all kinds of evil. Some have been led astray from the faith in their greed, and have pierced themselves through with many sorrows. 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.
It's understandable that your experiences have affected your view of God. But God is not silent or harsh, nor does He expect perfection. He is loving, kind, and merciful. Psalm 145:8-9 WEB Yahweh is gracious, merciful, slow to anger, and of great loving kindness. Yahweh is good to all; his loving kindness is over all his works.
You can find comfort in knowing that God hears your prayers. Psalm 34:17 WEB The righteous cry, and Yahweh hears, and delivers them out of all their troubles. He is close to the brokenhearted, Psalm 34:18 WEB Yahweh is near to those who have a broken heart, and saves those who have a crushed spirit. and He is the one who heals. Psalm 147:3 WEB He heals the broken in heart, and binds up their wounds.
Regarding what your mother called you during her confessions, it is not good to speak badly about someone who has died, Ecclesiastes 7:21-22 (WEB) Also don't give your heart to all words that are spoken, lest you hear your servant cursing you; 22 for often your own heart knows that you yourself have likewise cursed others., especially when it is someone who has caused you harm.
In light of this, let us pray:
Dear Heavenly Father,
We come before You, lifting up our sibling in Christ who has been deeply hurt by the actions of their parents. Lord, You see the pain and the wounds that have been caused, and we ask for Your healing touch. Help them to see You as You truly are—a loving, kind, and merciful Father.
Father, we pray for comfort and healing from the emotional abuse from the gambling and manipulation. We pray for complete financial restoration for the money that was taken. We pray for the lies that gambling is ok and they should have gone along with their parents to be reversed and the truth to be revealed by the Holy Spirit. We pray for complete closure for their mother's passing, including all the things that were said on her deathbed. We pray for complete healing of the deep pain and wounds.
Help them to trust in You and to know that You hear their prayers. Guide them in their relationship with You, and give them the strength to forgive those who have hurt them.
We ask for this all in Jesus' name. It is only by His name that we have access to God. Thank You for the gift of salvation through the name of Jesus Christ.
Prayer Focus: God, Thank You for loving me. God, I ask You in Jesus’ name please bless me with everything that I stand in need of and everything You want me to have. 
