Yes, you are being abused. I am sorry that is the case.
Insulting you, punishing you for no reason, threatening violence, and making you feel worthless and useless are all methods of abuse. So is invading your privacy. Those are abusive behaviors. You are the victim of what sounds like serious emotional abuse.
Abusers can be kind sometimes. Just because someone isn’t actively abusing you every second of the day does not negate the abuse they do.
Also, parents are obligated to buy things for and take care of their child. No matter what your parents say, feeding you and buying you clothes and possessions does not make them parent of the year, and it doesn’t make you obligated to them for it. They are obligated to you as their child. Failing to neglect you is not ‘above and beyond’. It is expected.
Here is some more information about emotional abuse, what it looks like, and how serious it can be. http://outofthefog.website/top-100-trait-blog/2015/11/4/emotional-abuse
Its hard to accept that people you love are abusing you. Once you can accept it however, it makes it easier to escape from, and heal from. Please feel free to read more of this blog, or contact me again if you have more questions about the abuse you’re going through, or how to get away from it.