I’m sorry you are having such a hard time. But I don’t think the way out of your anxiety and depression is to try to make your mother be someone she isn’t. I don’t have enough information to understand why your mother lies and criticizes you and, especially, why on earth she would take your medication. But I don’t have to understand her. Nothing I say will make her change. Nothing you do will either.
So let’s look at what you can do to help yourself. You are now 18, a time when it is important to be working on yourself to get ready to be on your own. Clearly the anxiety and depression you struggle with isn’t going to help you launch into adulthood as successfully as you would like. Since you can’t count on your mom to help you, it’s long past time to find people who can.
First, do look for other role models for adult behavior. Kids like yourself often find the support, wisdom, and advice they need from someone other than their parents. I hope you have an older woman relative, a teacher, a coach, or the mom of a good friend to talk to.
Second: Please do consider getting some therapy. Anxiety and depression are treatable. There is no need to live with it. Cutting obviously only adds another problem to the ones you already have.
If your school has a counseling center, start there. They may offer some therapy or they may keep a list of free or low cost mental health services in the area. If they can’t help, tell your mother that you need help with your anxiety and ask her whether your family health insurance covers therapy. (You are more likely to get somewhere with this request if you don’t angrily tell her that your anxiety is all her fault. Just say that you know you need some help and leave it at that.) If so, the insurance company probably has a list of approved providers. If not, your doctor can also probably refer you to services.
In the meantime, be the mother to yourself that your mom can’t be. Make sure you are treating yourself better than your mother is. Do some self-care. Eat well. Get 8 hours of sleep a night. Get outside regularly. Learn a self-calming method like meditation. You can also read books and do the exercises in workbooks that provide ways to handle anxiety and depression.
You might find it helpful to join one of the forums here at Psych Central. People from all over the world offer each other support and help. Although it isn’t a substitute for therapy, it can be reassuring to know that you are not alone and people often have good practical advice.
I wish you well.