This is a difficult question, and maybe even sensitive for some, because we know that Islam unequivocally condemns abuse or physical violence towards other innocent people.
We must always remember that many parents have not been given the correct method of upbringing, and many parents do not have the adequate skills to deal with parenting and the many pressures that it entails.
As Muslims, we are taught to always show the utmost level of respect to our parents and our elders. How they reciprocate that and what they do or have done is something else.
Allah ta'ala will judge them for what they have done.
We must stay loyal to our parents, pray for them, visit them, be compassionate to them, and never sever ties with them. We must also ask Allah ta'ala to grant us the patience we need to make sure our love for them stays in our heart, even thought they might have hurt us.
As long as you yourself know that you are not being insolent, or disobeying your parents, or not cutting ties. In regards to your inner feelings, there is nothing much that are able to do, because of the ongoing abuse, but it still does not allow you to disrespect your parents.
Honour your parents, avoid things that would agravate them, or upset them, in what you do or say, try to get them to understand your position, and how its affecting you, maybe by getting intervention from elders, and most importantly always do dua for them.
With prayers for your success.