You are not the one who caused this situation. Anytime any of us have difficulty we were impacted by many things. Research has shown that anxiety and depression involve chemical changes in the brain. That is why medication is combined with counseling. Trying different meds is a part of the process to find the right combination of our body and helpful meds.
You have received good advice from other moms. Their experiences seem to be similar to yours. I believe they have given you advice that has helped them.
Is your daughter 18 and an adult. I wrote the following based on her being a teen still under your control as a parent. If she is chronologically an adult change some of my answers to help her to.......see a psychiatrist. I don't know how cooperative she is.
I know from my experience with myself that taking care of myself is an important part of living with a situation such as yours. Eating healthy, getting a healthy amount of sleep and exercise is important. Of course you're overwhelmed and anxious. I suggest you will benefit from some medication for yourself.
My other suggestion related to having some control over this situation is to never argue with her. Step away. Leave the room. This is one if those things we have to "fake it until we make it."
I had support from friends and counselors. Support is very important for our own mental health. NAMI can be helpful in that way. I hope you know some women with whom you can develop a casual relationship. Just being with someone, without talking about or getting support from them, will give you a break from the heavy responsibility you feel. How old are your other children? Get involved with their activities. Take your young son to activities you both enjoy.
If you haven't taken her to a psychiatrist or psychologist for a more thorough diagnosis, make an appointment to do so.
Depression and anxiety can cause this sort of behaviour. Depression and activity can be a form of mental illness. That diagnoses is a part of a medical chart.
Because she's a teen, I suggest some of her behaviour is related to teen issues. Parenting a teen is different than parenting a younger child. Some teens, especially depressed teens, have some difficulty adjusting to hormonal changes. They sre often expected to be more mature than they may be capable of being. Some kids react to the pressure of being a teen with depression and anger. They show there insecurity by trying to be in control of other people. This, along with a lack of working boundaries, could explain being abusive to siblings. All that you describe could be explained as a reaction to anxiety and depression.
If she's not regularly seeing a counselor, I suggest she needs a counselor that she can learn to trust. I suggest that you will benefit from counseling for yourself as you navigate the teen years. A counselor will give you support as well.
Also learn about how to communicate with teens. I recommend 2 books. One is How to Talk So Kids will Listen and How to Listen So Kids Will Talk by Adele Faber. There may be the same book directed towards teen behaviour. I also suggest parenting books writen about Love and Logic. Love and Logic has a web site as well as several books.
Kids need boundaries with immediate, consistent rational consequences. Consequences related to their behaviour. They need to know parents love them no matter what they do. Love and Logic describes how to do both for children and Teens. I parented a daughter and then a teen granddaughter. Both of these changed the way I disciplined. I was able to gradually change the way I thought about parenting with the support of counselors.
I've been anxious and depressed my entire life. Once there was available medication I was able to benefit more from counseling. Both my daughter and granddaughter take antidepressant and antidepressant meds. I see a change in how they face life. Medication paired with talk therapy makes a difference over time.
We have all had medication changes until we and the doctor found those who work best for each one of us. Finding the one that works best is trying out different meds. Both my daughter, as a teen, and my teen granddaughter resisted taking meds. They said the meds didn't help. However, I saw a subtle difference. My daughter is taking meds and now says they help her moderate her moods. My adult daughter is in counseling now.
I empathize with you. Parenting teens, at the best, is difficult. When our teen and ourselves are anxious and depressed it's 10 times worse. Know that life will get better.