Im 100% serious i need ur help
I Corinthians 6:
10 Nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners, shall inherit the kingdom of God. (This is God's promise to you)
11And such were some of you: but ye are washed, but ye are sanctified, but ye are justified in the name of the Lord Jesus, and by the Spirit of our God. (God wants you to know you can be forgiven if you ask for it and try to change your ways)
12 All things are lawful unto me, but all things are not expedient: all things are lawful for me, but I will not be brought under the power of any. (Don't let drugs and evil things control your life because you are better than that)
You don't pay her back the money. Parents know that money comes and goes. You pay her back by trusting her to love you no matter what you may have done.
I don't know your family situation. Most parents greatest wish is a healthy and happy child. Tell her what has occurred if you have a decent family. She will be shocked, scared, and upset all at once. This is a good thing as it is normal. She may ask you to slowly repay the money in order to teach you a lesson, but I doubt it. If so, it is out of love not hatred or spite.
We all do things that we may later regret. You are not the first and definitely will not be the last. Trust your mother to love you regardless, especially if you go to her before anything worse happens.
If you don't feel that you can, then please find a counselor to talk to. When you initiate the discussion, people automatically become proud of your courage to do so and respect you regardless of what has happened.